FermCalc is a collection of advanced winemaking calculators designed to assist both amateur and professional winemakers with calculations related to the following activities:

• Unit conversions
• Chaptalization/dilution
• Acidity adjustment
• Sulfite additions
• Alcohol content estimation
• Blending
• Fortification
• Miscellaneous additions

All of the calculators employ a standardized layout.  Fields and options that can be changed by the user are shaded lighter.  Output fields are shaded darker.  Full flexibility is provided for specifying both input and output units.  Examples of input and output fields are shown below.

To get started, go to the Settings menu to set your preferred unit system and default temperatures.

To perform a calculation, follow these three general steps:

1. Select options – Select the appropriate options from the available radio-button lists or drop-down lists.
2. Select units – Make any desired changes to the unit selections for each of the input and output fields.  When the unit selections are changed, the values in the field are changed to reflect the new unit selection.
3. Enter values – Enter the required values in the input fields.

Calculated values will appear in the output fields when the necessary input data are provided.  Errors will be flagged with a red error message down below the calculator.  Negative values will generally be ignored (assumed to be zero) except for certain specific gravity, temperature, and refractivity units.  High-level descriptions of each of the calculators and descriptions of the input and output fields can be accessed by clicking on the help (question mark) icon at the upper right.

For details regarding the mathematics involved in the calculations, see the calculation details pages at FermCalc.com.

By using FermCalc, you agree to the End User License Agreement and to the FermCalc Privacy Policy.

Calculator Descriptions

Chaptalization & Dilution – The Chaptalization & Dilution Calculator determines the amounts of sweetener and/or water to add to a given must to achieve a target specific gravity (SG) and volume.  Alternatively, the resulting SG and volume can be calculated from the specified sweetener and water additions.  The sweetener can be either sugar, honey, or concentrate.

Amelioration – Amelioration is the dilution of must with water in order to reduce the acidity or sugar content.  The Amelioration Calculator determines the required additions of water, sugar, and acid to a must to meet the desired acidity and SG levels given the initial acidity, initial SG, and initial must volume.  Alternatively, the target must volume can be specified, in which case FermCalc calculates the initial volume of must required, along with the required water, acid, and sugar additions.

High Brix Measurement by Dilution – The High Brix Measurement by Dilution Calculator determines the specific gravity of a liquid from a specific gravity measurement after it has been diluted with a given volume of water.  This calculation is useful for determining the specific gravity of high-Brix liquids such as honey or concentrates with specific gravities that are outside of the range of standard hydrometers or refractometers.

Calculator Descriptions

Acid Titration – The Acid Titration Calculator determines the titratable acidity (TA) of a wine sample given the volume of the sample and the volume of sodium hydroxide (NaOH) added during a titration test.

Acidification & Deacidification – The Acidification & Deacidification Calculator determines the amount of a selected acid or deacidifier required to increase or decrease the acidity of a wine from its current value to some target value.  If the target acidity is greater than the initial acidity, a list of acids will be shown.  If the target acidity is less than the initial acidity, a list of deacidifiers will be shown.

Amelioration – Amelioration is the dilution of must with water in order to reduce the acidity or sugar content.  The Amelioration Calculator determines the required additions of water, sugar, and acid to a must to meet the desired acidity and SG levels given the initial acidity, initial SG, and initial must volume.  Alternatively, the target must volume can be specified, in which case FermCalc calculates the initial volume of must required, along with the required water, acid, and sugar additions.

NaOH Standardization – The NaOH Standardization Calculator determines the normality of your sodium hydroxide (NaOH) solution from the titration of a potassium hydrogen phthalate (KHP) solution of known normality.

Calculator Descriptions

Hydrometer SG Drop – The Hydrometer SG Drop Calculator estimates the alcohol content of a wine from two specific gravity (SG) measurements: one obtained prior to fermentation, and one obtained after fermentation is complete.  Four different calculation methods are used to estimate alcohol content:

• Berry
• Duncan & Acton
• Balling
• Cutaia, Reid, & Speers

Hydrometer & Refractometer – The Hydrometer and Refractometer Calculator estimates the alcohol content of a finished wine from a refractometer reading and a hydrometer specific gravity (SG) reading.  Four different calculation methods are used to estimate alcohol content:

• Rogerson & Symington
• Son et al.
• Roesener
• Barth & Race

Boiling (Spirit Indication) – The Boiling (Spirit Indication) Calculator estimates the alcohol content of a wine from two specific gravity (SG) measurements: one obtained on a sample of the finished wine, and one obtained on a sample of the wine in which the alcohol has been boiled off and distilled water has been added to restore it to its pre-boiled volume.  Four different calculation methods are used to estimate alcohol content:

• Tabarié (Division)
• Blunt (Subtraction)
• Honneyman
• Hackbarth

Potential Alcohol – The Potential Alcohol Calculator estimates the alcohol content of a wine that will result from the complete fermentation of a must with a given initial specific gravity.  Nine methods are used to estimate the potential alcohol content:

• Dubrunfaut
• Marsh
• Margalit
• Cooke & Lapsley
• CEC
• Pambianchi
• Duncan & Acton
• Honneyman
• User Defined

OIML Calculator – The OIML Calculator solves the general formula for calculating the densities of mixtures of ethanol and water found in International Recommendation 22: International Alcoholometric Tables by the International Organisation of Legal Metrology (OIML).

Dry Matter Calculator - The Dry Matter Calculator determines the solids content of a wine from its alcohol content and specific gravity.  This is useful for winemakers who determine the alcohol content of their wines by other means, such as distillation or ebulliometry, and would like to calculate solids content.  Two methods are used to determine the solids content:

• OIV
• Hackbarth

Calculator Descriptions

Post-Fermentation Fortification – The Post-Fermentation Fortification Calculator determines the amounts of fortifier and sweetener to add to a given wine to yield a fortified wine with the desired alcohol content, sugar content, and volume.  Alternatively, the resulting alcohol content, sugar content, and volume can be calculated from the specified fortifier and sweetener additions.  The sweetener can be either sugar, honey, or concentrate.

Fortification Point – The Fortification Point Calculator determines 1) the specific gravity (SG) at which to stop an active fermentation to yield the desired level of residual sugar in a fortified wine, and 2) the amount of fortifier required yield the desired alcohol level.  It accounts for the alcohol produced during fermentation, and for the dilution of the residual sugar by the addition of the fortifier.

Hackbarth SG Calculator – The Hackbarth SG Calculator utilizes the Hackbarth model to estimate SG from given values of alcohol content and sugar content.  Its purpose is mainly to test and validate the Hackbarth calculation in FermCalc, but it is also useful in the preparation of fortified wines and liqueurs.

Calculator Descriptions

Dry Measure Converter – The Dry Weight/Volume Converter converts between dry weight (mass) and dry volume for a number of common winemaking additives.  This calculator is intended mainly for home winemakers who don't have accurate scales, and instead add ingredients on the basis of dry volumes (teaspoons, mL, etc.).

Stock Solutions – The Stock Solution Formulation Calculator determines the amount of an additive required to yield a stock solution with a given volume and concentration.

Inverse Stock Solutions – The Inverse Stock Solution Makeup Calculator determines the amount of an additive required to yield a stock solution such that a specific volume of the solution will result in a desired increase in concentration of the additive in a specific volume of wine.

Miscellaneous Additions – The Miscellaneous Additions Calculator determines the amount of an additive to add to a wine to yield a desired concentration in the wine, given the initial concentration of the additive and volume of the wine. The additive can either be in the form of a solid (powder or crystals) or a liquid (stock solution).

Yeast Assimilable Nitrogen – The Yeast Assimilable Nitrogen (YAN) Calculator determines the amount yeast nutrients required to supply the desired YAN level in a must.  The total YAN requirement is calculated based on the nitrogen requirements of the selected yeast strain and on the initial SG of the must.  The required masses of the selected nutrients are then calculated based on their nitrogen contents.  The additions can be scheduled in stages, with up to three nutrients added in up to four stages.

The Unit Conversions Calculator performs unit conversions for the following unit categories:

• Volume
• Mass
• Temperature
• Specific Gravity / Density
• Acidity
• Alcohol Content
• Concentration
• Refractivity

All specific gravity (SG), density, alcohol content, and refractivity conversions have a temperature basis of 20°C (68°F).  The SG conversions that involve sugar content (°Brix and g/l sugar) are based on the densities of sucrose-water solutions.  The conversions between refractive index and other refractometer scales (°Brix, °Oe, °Baumé, and °KMW) are based on the refractivities of sucrose-water solutions.

For details regarding the mathematics involved in the calculations, see the calculation details pages at FermCalc.com.

Input Field Definitions

Input Value – The value of the quantity to be converted at the specified input units.

Output Field Definitions

Output Value – The converted value at the specified output units.

The Chaptalization & Dilution Calculator determines the amounts of sweetener and/or water to add to a given must to achieve a target specific gravity (SG) and volume.  Alternatively, the resulting SG and volume can be calculated from the specified sweetener and water additions.  The sweetener can be either sugar, honey, or concentrate.

FermCalc offers three options for this calculation:

1. Specify target SG  >  Calculate water/sugar additions and volume – Specify the target SG, the initial SG, and the initial volume, and FermCalc will calculate the required additions of water or sweetener as well as the resulting volume after the addition.
2. Specify target SG & volume  >  Calculate water/sugar additions – Specify the target SG, the initial SG, the target volume, and the initial volume, and FermCalc will calculate the required additions of water and/or sweetener to achieve both targets.
3. Specify water/sugar additions  >  Calculate resulting SG & volume – Specify the initial SG, the initial volume, and the amounts of water and/or sugar to be added, and FermCalc will calculate the resulting volume and SG.

All volumes and specific gravities have a temperature basis of 20°C (68°F).

For details regarding the mathematics involved in the calculations, see the calculation details pages at FermCalc.com.

Input Field Definitions

Sweetener – The type of sweetener to be added, either sugar, honey, or concentrate.  The SG of the sweetener must be specified if honey or concentrate is selected.

Target SG – The desired SG (20°C/20°C) of the must after chaptalization or dilution.  Required only if either the first or second calculation option is selected.  Range: 0.77193 to 1.55454

Initial SG – The SG (20°C/20°C) of the must prior to chaptalization or dilution.  Range: 0.77193 to 1.55454

Target Volume – The desired volume of the must after chaptalization or dilution.  Required only if the second calculation option is selected.

Initial Volume – The volume of the must prior to chaptalization or dilution.  Required only if either the first or third calculation option is selected.

Sugar (or Honey or Concentrate) Added – The amount of sweetener added to the must.  Required only if the third calculation option is selected.

Water Added – The amount of water added to the must.  Required only if the third calculation option is selected.

Output Field Definitions

Sugar (or Honey or Concentrate) Required – The calculated amount of sweetener required to yield the desired specific gravity and volume.  Reported only if either the first or second calculation option is selected.

Water Required – The calculated amount of water required to yield the desired specific gravity and volume.  Reported only if either the first or second calculation option is selected.

Resulting SG – The SG (20°C/20°C) of the must after adding the specified amounts of sweetener and water.  Reported only if the third calculation option is selected.

Resulting Volume – The calculated volume of the must after adding the specified amounts of sweetener and water.  Reported only if the third calculation option is selected.

The High Brix Measurement by Dilution Calculator determines the specific gravity of a liquid from a specific gravity measurement after it has been diluted with a given volume of water.  This calculation is useful for determining the specific gravity of high-Brix liquids such as honey or concentrates with specific gravities that are outside of the range of standard hydrometers or refractometers.

The calculator will adjust the hydrometer reading for temperature if the measurement temperature and the hydrometer calibration temperature are provided.  If the entered SG value is already corrected for temperature, or if temperature corrections are not desired, simply enter 20°C (68°F) in both of the temperature fields and no corrections will be made.  The temperature correction is applied only to the hydrometer reading and not to the liquid volumes.  The temperatures of the original liquid and the added water should be about the same so that the correct dilution ratio is used in the calculation.

The accuracy of this calculation is highly dependent on how thoroughly the diluted sample is mixed.  If the diluted sample is not mixed well, the measured SG might not be representative of the mixture, which would result in an inaccurate SG estimate for the original liquid.

For details regarding the mathematics involved in the calculations, see the calculation details pages at FermCalc.com.

Input Field Definitions

Measurement Type – Select from hydrometer or refractometer.  Hydrometer measurements will be temperature corrected if desired.

Sample Volume – The original volume of the sample to be diluted.

Water Added – The volume of water added to dilute the sample.

Refractometer Reading – The refractometer reading for the diluted sample.  Required only if refractometer was selected as the measurement type.  Range: 0° to 100°Brix

Hydrometer SG Reading – The hydrometer SG reading for the diluted sample.  Required only if hydrometer was selected as the measurement type.  Range: 0.77193 to 1.55454

SG Reading Temperature – The temperature of the diluted sample at the time of the SG reading.  Required only if hydrometer was selected as the measurement type.  Range: 0°C (32°F) to 40°C (104°F)

Calibration Temperature – The hydrometer calibration temperature of the hydrometer used to take SG reading. Required only if hydrometer was selected as the measurement type.    Range: 0°C (32°F) to 40°C (104°F)

Output Field Definitions

Corrected SG (20°C/20°C) – The temperature-corrected SG value.  Reported only if hydrometer was selected as the measurement type.

Calculated Sample SG – The calculated SG of the original sample prior to dilution.

Diluted Volume – The calculated volume of the diluted sample, which is not simply the sum of the sample and water volumes because of solution effects.

The Acid Titration Calculator determines the titratable acidity (TA) of a wine sample given the volume of the sample and the volume of sodium hydroxide (NaOH) added during a titration test.

For details regarding the mathematics involved in the calculations, see the calculation details pages at FermCalc.com.

Input Field Definitions

Wine Sample Volume – The volume of the wine sample being titrated.

Volume of NaOH Added – The volume of NaOH solution required to reach the titration endpoint.

NaOH Normality – The normality (moles/liter) of the NaOH solution used to titrate the wine sample.

Output Field Definitions

Titratable Acidity (TA) – The calculated titratable acidity of the wine sample.

The Acidification & Deacidification Calculator determines the amount of a selected acid or deacidifier required to increase or decrease the acidity of a wine from its current value to some target value.  If the target acidity is greater than the initial acidity, a list of acids will be shown.  If the target acidity is less than the initial acidity, a list of deacidifiers will be shown.

Acid blend is assumed to be a blend of 40% tartaric, 40% malic, and 20% citric acids.

For details regarding the mathematics involved in the calculations, see the calculation details pages at FermCalc.com.

Input Field Definitions

Target Acidity – The desired acidity of the wine.

Initial Acidity – The current acidity of the wine.

Wine Volume – The volume of wine being treated.

Acid Type – The acid to be used to treat the wine. The list of acids will be shown if the target acidity is greater than the initial acidity.  Acid blend is assumed to be a blend of 40% tartaric, 40% malic, and 20% citric acids.

Deacidifier Type – The deacidifying agent to be used to treat the wine.  The list of deacidifiers will be shown if the target acidity is less than the initial acidity.

Output Field Definitions

Acid Required – The calculated mass of the selected acid required to achieve the target acidity.

Deacidifier Required – The calculated mass of the selected deacidifier required to achieve the target acidity.

Amelioration is the dilution of must with water in order to reduce the acidity or sugar content.  When diluting to reduce the acidity, it is often necessary to add sugar to maintain the potential alcohol level of the must.  When diluting to reduce sugar content, it is often necessary to add acid to bring the acidity up to an acceptable level. 

The Amelioration Calculator determines the required additions of water, sugar, and acid to a must to meet the desired acidity and SG levels given the initial acidity, initial SG, and initial must volume.  Alternatively, the target must volume can be specified, in which case FermCalc calculates the initial volume of must required, along with the required water, acid, and sugar additions.

For details regarding the mathematics involved in the calculations, see the calculation details pages at FermCalc.com.

Input Field Definitions

Acid Type – The type of acid being added, either tartaric, malic, citric, or acid blend.  Acid blend is assumed to be a blend of 40% tartaric, 40% malic, and 20% citric acids.

Sweetener – The type of sweetener to be added, either sugar, honey, or concentrate.  The SG of the sweetener must be specified if honey or concentrate is selected.

Target Acidity – The desired acidity of the must after the water/sugar/acid additions.  Range: 0 to 100 grams/liter.

Initial Acidity – The acidity of the must prior to the water/sugar/acid additions.  Range: 0 to 100 grams/liter.

Target SG – The desired specific gravity of the must after the water/sweetener/acid additions.  Range: 0.77193 to 1.55454

Initial SG – The specific gravity of the must prior to the water/sweetener/acid additions.  Range: 0.77193 to 1.55454

Must Volume – The volume of the must prior to the water/sweetener/acid additions.

Target Volume – The desired volume of the must after the water/sweetener/acid additions.

Output Field Definitions

Water Required – The volume of water required to meet the target acidity, SG, and volume.

Sugar (or Honey or Concentrate) Required – The amount of sweetener required to meet the target acidity, SG, and volume.

Acid Required – The mass of acid required to meet the target acidity, SG, and volume.

Resulting Volume – The volume of the must after adding the water, sweetener, and acid.  Reported only if Must Volume is selected above.

Must Required – The volume of the juice required to meet the target acidity, SG, and volume.  Reported only if Target Volume is selected above.

The NaOH Standardization Calculator determines the normality of your sodium hydroxide (NaOH) solution from the titration of a potassium hydrogen phthalate (KHP) solution of known normality.

For details regarding the mathematics involved in the calculations, see the calculation details pages at FermCalc.com.

Input Field Definitions

KHP Volume – The volume of KHP solution being titrated.

KHP Normality – The normality of the KHP solution being titrated.

Volume of NaOH Added – The volume of NaOH solution required to reach the titration endpoint.

Output Field Definitions

NaOH Normality – The calculated normality of the NaOH solution.

The Sulfite Calculator determines the amount of potassium or sodium metabisulfite to add to a given volume of wine in order to achieve the desired concentration of sulfur dioxide (SO2) in the wine.  The target can be specified in terms of free SO2 or molecular SO2.

For details regarding the mathematics involved in the calculations, see the calculation details pages at FermCalc.com.

Input Field Definitions

Target Type – The type of SO2 concentration target, either free SO2 or molecular SO2.

Sulfite Type – The type of metabisulfite to be added to the wine, either potassium metabisulfite or sodium metabisulfite.

Sulfite Form – The form of the metabisulfite being added to the wine, either campden tablets, powder/crystals, or stock solution.

Campden Tablet Sulfite Mass – The mass of the sodium or potassium metabisulfite in the campden tablets being used.  This is most commonly 440 mg or 550 mg.  This is not the total mass of the tablets because campden tablets also contain inert fillers and binders in addition to sulfites.

Stock Solution Concentration – The concentration of the stock solution, required only if stock solution is selected as the sulfite form.

Target Free SO2 – The target free SO2 concentration in the wine, required only if free SO2 was selected as the target type.

Target Molecular SO2 – The target molecular SO2 concentration in the wine, required only if molecular SO2 was selected as the target type.

Initial Free SO2 – The current free SO2 concentration in the wine.

Wine Volume – The volume of the wine being sulfited.

Wine pH – The pH of the wine being sulfited.  This value is used with the equilibrium constant to relate free SO2 concentration and molecular SO2 concentration.  It is required only if molecular SO2 was selected as the target type, or if an estimate of molecular SO2 is desired.  Range: 0 to 14

SO2 Equilibrium Constant – The equilibrium constant (pKa) of SO2.  This value is used with the pH to relate free SO2 concentration and molecular SO2 concentration.  It is required only if molecular SO2 was selected as the target type, or if an estimate of molecular SO2 is desired.  Range: 1.75 to 1.85

Output Field Definitions

Resulting Molecular SO2 – The calculated molecular SO2 concentration, reported only if free SO2 is selected as the target type.

Resulting Free SO2 – The calculated free SO2 concentration, reported only if molecular SO2 is selected as the target type.

Campden Tablets Required – The calculated number of campden tablets required to achieve the target SO2 concentration, reported only if campden tablets was selected as the sulfite form.

Powder/Crystals Required – The calculated mass of metabisulfite powder/crystals required to achieve the target SO2 concentration, reported only if powder/crystals was selected as the sulfite form.

Stock Solution Required – The calculated volume of stock solution required to achieve the target SO2 concentration, reported only if stock solution was selected as the sulfite form.

The Hydrometer SG Drop Calculator estimates the alcohol content of a wine from two specific gravity (SG) measurements: one obtained prior to fermentation, and one obtained after fermentation is complete.  Four different calculation methods are used to estimate alcohol content:

• Berry
• Duncan & Acton
• Balling
• Cutaia, Reid, & Speers

The calculator will adjust the hydrometer readings for temperature if the measurement temperatures and the hydrometer calibration temperatures are provided. If the entered SG values are already corrected for temperature, or if temperature corrections are not desired, simply enter 20°C (68°F) in all of the temperature fields and no corrections will be made.

This calculation is only valid for SG or density measurements obtained with a hydrometer or some other device for directly measuring SG or density.  It does not work with refractometer readings because of the obscuration effect of alcohol on refractive index.  The final SG measurement must be taken prior to any post-fermentation sweetening.  If any sweetener is added during fermentation after the initial SG measurement is taken, the initial SG measurement must be adjusted accordingly.

For details regarding the mathematics involved in the calculations, see the calculation details pages at FermCalc.com.

Input Field Definitions

Hydrometer SG Reading – The initial and final hydrometer SG readings.  The initial reading should be taken prior to fermentation, and the final SG reading should be taken after fermentation is complete.  Range: 0.77193 to 1.55454

SG Reading Temperature – The temperatures of the must and wine samples at the time of the initial and final SG readings.  Range: 0°C (32°F) to 40°C (104°F)

Calibration Temperature – The hydrometer calibration temperature(s) of the hydrometer(s) used to take the initial and final SG readings.   Range: 0°C (32°F) to 40°C (104°F)

Output Field Definitions

Corrected SG (20°C/20°C) – The temperature-corrected initial and final SG values.

Alcohol Content – The alcohol content of the wine calculated from the difference between the initial and final corrected SG values using the four calculation methods listed above.

True Brix (Solids Content) – The total solids content of the wine calculated from the final corrected SG value and the average alcohol content of the four calculation methods.

The Hydrometer and Refractometer Calculator estimates the alcohol content of a finished wine from a refractometer reading and a hydrometer specific gravity (SG) reading.  Four different calculation methods are used to estimate alcohol content:

• Rogerson & Symington
• Son et al.
• Roesener
• Barth & Race

The calculator will adjust the hydrometer reading for temperature if the measurement temperature and the hydrometer calibration temperature are provided.  If the entered SG value is already corrected for temperature, or if temperature correction is not desired, simply enter 20°C (68°F) in both of the temperature fields and no correction will be made.

For details regarding the mathematics involved in the calculations, see the calculation details pages at FermCalc.com.

Input Field Definitions

Refractometer Reading – The refractometer reading for the wine after fermentation.  Range: 0° to 100°Brix

Hydrometer SG Reading – The hydrometer SG reading for the wine sample.  Range: 0.77193 to 1.55454

SG Reading Temperature – The temperature of the wine sample at the time of the SG reading.  Range: 0°C (32°F) to 40°C (104°F)

Calibration Temperature – The hydrometer calibration temperature of the hydrometer used to take SG reading.   Range: 0°C (32°F) to 40°C (104°F)

Output Field Definitions

Corrected SG (20°C/20°C) – The temperature-corrected SG value.

Alcohol Content – The alcohol content of the wine calculated using the four calculation methods listed above.

True Brix – The total solids content of the wine calculated using the four calculation methods listed above.

The Boiling (Spirit Indication) Calculator estimates the alcohol content of a wine from two specific gravity (SG) measurements: one obtained on a sample of the finished wine, and one obtained on a sample of the wine in which the alcohol has been boiled off and distilled water has been added to restore it to its pre-boiled volume.  Four different calculation methods are used to estimate alcohol content:

• Tabarié (Division)
• Blunt (Subtraction)
• Honneyman
• Hackbarth

The calculator will adjust the hydrometer readings for temperature if the measurement temperatures and the hydrometer calibration temperatures are provided.   If the entered SG values are already corrected for temperature, or if temperature corrections are not desired, simply enter 20°C (68°F) in all of the temperature fields and no corrections will be made.

For details regarding the mathematics involved in the calculations, see the calculation details pages at FermCalc.com.

Input Field Definitions

Hydrometer SG Reading – The initial and final hydrometer SG readings.  The initial reading should be taken prior to boiling, and the final SG reading should be taken after boiling off the alcohol and restoring the sample to its original volume with distilled water.  Range: 0.77193 to 1.55454

SG Reading Temperature – The temperatures of the samples at the time of the initial and final SG readings.  Range: 0°C (32°F) to 40°C (104°F)

Calibration Temperature – The hydrometer calibration temperature(s) of the hydrometer(s) used to take the initial and final SG readings.   Range: 0°C (32°F) to 40°C (104°F)

Output Field Definitions

Corrected SG (20°C/20°C) – The temperature-corrected initial and final SG values.

Alcohol Content – The alcohol content of the wine calculated from the difference between the initial and final corrected SG values using the four calculation methods listed above.

True Brix (Solids Content) – The total solids content of the wine calculated from the initial and final corrected SG values.

The Potential Alcohol Calculator estimates the alcohol content of a wine that will result from the complete fermentation of a must with a given initial specific gravity.  Nine methods are used to estimate the potential alcohol content:

• Dubrunfaut
• Marsh
• Margalit
• Cooke & Lapsley
• CEC
• Pambianchi
• Duncan & Acton
• Honneyman
• User Defined

Most of these methods assume some sugar to alcohol conversion factor less than the theoretical maximum of 0.511 grams of alcohol per gram of sugar.  Most of them also make an allowance for the presence of non-fermentable solids, most commonly assumed to be 30 g/L.  The actual alcohol content will depend on the composition of the must and on the efficiency and completeness of the fermentation, so it is best measured after fermentation is finished. 

Because of the approximate nature of these calculations, no temperature corrections are made to the SG or to the calculated alcohol contents.  The SG measurement should be made near 20°C (68°F). 

For details regarding the mathematics involved in the calculations, see the calculation details pages at FermCalc.com.

Input Field Definitions

Initial Must SG – The SG (20°C/20°C) of the must prior to the start of fermentation.  Range: 1.0 to 1.5545 (0° to 100° Brix).

Fermentation Factor – This is the factor multiplied by Brix in the User Defined method.  A range is not enforced, but this is usually in the range between 0.55 and 0.63.

Output Field Definitions

Potential Alcohol Content – The estimated alcohol content after complete fermentation.

The OIML Calculator solves the general formula for calculating the densities of mixtures of ethanol and water found in International Recommendation 22: International Alcoholometric Tables by the International Organisation of Legal Metrology (OIML).

For details regarding the mathematics involved in the calculations, see the calculation details pages at FermCalc.com.

Input Field Definitions

Density – The density of the ethanol/water mixture.  This field can be either an input field or an output field.  If it is used as an input field, the alcohol content is calculated from the entered values of density and temperature.  If alcohol content is entered, density is calculated.  Range: 771.93 to 1000 kg/m³

Temperature – The temperature at which to calculate the density or alcohol content for the ethanol/water mixture.  If the temperature is changed, either the density or alcohol content will be recalculated, depending on which one was entered last.  Range: -20°C (-4°F) to 40°C (104°F)

Alcohol Content – The alcohol content of the ethanol/water mixture.  This field can be either an input field or an output field.  If it is used as an input field, the density is calculated from the entered values of alcohol content and temperature.  If density is entered, alcohol content is calculated.  Range: 0% to 100% vol/vol

The Dry Matter Calculator determines the solids content of a wine from its alcohol content and specific gravity.  This is useful for winemakers who determine the alcohol content of their wines by other means, such as distillation or ebulliometry, and would like to calculate solids content.  Two methods are used to determine the solids content:

• OIV
• Hackbarth

The calculator will adjust the hydrometer reading for temperature if the measurement temperature and the hydrometer calibration temperature are provided.  If the entered SG value is already corrected for temperature, or if temperature corrections are not desired, simply enter 20°C (68°F) in both of the temperature fields and no corrections will be made.

This calculation is only valid for SG or density measurements obtained with a hydrometer or some other device for directly measuring SG or density.  It does not work with refractometer readings because of the obscuration effect of alcohol on refractive index.

For details regarding the mathematics involved in the calculations, see the calculation details pages at FermCalc.com.

Input Field Definitions

Alcohol Content – The alcohol content of the wine.  Range: 0% to 100% vol/vol

Hydrometer SG Reading – The hydrometer SG reading for the wine sample.  Range: 0.77193 to 1.55454

SG Reading Temperature – The temperature of the wine sample at the time of the SG reading.  Range: 0°C (32°F) to 40°C (104°F)

Calibration Temperature – The hydrometer calibration temperature of the hydrometer used to take SG reading.   Range: 0°C (32°F) to 40°C (104°F)

Output Field Definitions

Corrected SG (20°C/20°C) – The temperature-corrected SG value.

True Brix (Solids Content) – The total solids content of the wine calculated from alcohol content and the corrected SG value.

The Blending Calculator determines the resulting property and volume of a blend of two liquids given the properties and volumes of the liquids being blended.  It can also determine the volumes of the two liquids required to achieve desired values of the blend's property and volume.  Three calculation options are offered:

1. Solve for Property and Volume of Blend – Given the properties and volumes of liquids 1 and 2, the property and volume of the blend will be calculated.
2. Solve for Volumes of Liquid 2 and Blend – Given the property and volume of liquid 1, the property of liquid 2, and the desired property of the blend, the volumes of liquid 2 and the blend will be calculated.
3. Solve for Volumes of Both Liquids – Given the properties of liquids 1 and 2, and the desired property and volume of the blend, the volumes of liquids 1 and 2 will be calculated.

In Standard mode, the Blending Calculator employs an ideal, volume-weighted mixing rule to calculate the resulting properties and volume of a blend from the properties of the constituent liquids being blended.  This is equivalent to a Pearson's Square calculation.  This calculation will yield accurate results for just about any concentration that is expressed in terms of mass per unit volume or volume per unit volume, such as specific gravity, alcohol content, acidity, residual sugar, etc.  However, it does not work well for pH because pH is the negative log of a concentration, and it must be converted to a concentration prior to making the calculation.  It will also not work well for properties expressed as mass per unit mass, such as Brix, in which case mass balance equations must be used.

In Advanced mode, the calculation depends on the type of property being calculated.  The calculator currently offers three property types:  Concentration, pH, and Specific Gravity/Density.

For details regarding the mathematics involved in the calculations, see the calculation details pages at FermCalc.com.

Input Field Definitions

Standard, Advanced – Select between Standard and Advanced mode.  In Standard mode, a standard "Pearson's Square" calculation is performed regardless of the property type.  In Advanced mode, the calculation depends on the property type:  concentration calculations are the same as those used in Standard mode; pH is first converted to a concentration before performing the calculation; and SG / Density calculations are performed using a separate set of mass balance equations.

Property Type – Select from Concentration, pH, or Specific Gravity / Density. Required only in Advanced mode.

SG Units – Select the units for which SG will be entered and output. Required only in Advanced mode when Specific Gravity / Density is chosen as the property type.

Liquid 1 & 2 Property – The properties (SG, acidity, etc.) of the two liquids being blended.

Liquid 1 & 2 Volume – The volumes of the two liquids being blended.  These fields can be either input fields or output fields depending on the calculation option selected.

Blend Property – The property of the blend of the two liquids.  This field can be either an input field or an output field depending on the calculation option selected.

Blend Volume – The volume of the blend of the two liquids.  This field can be either an input field or an output field depending on the calculation option selected.

The Post-Fermentation Fortification Calculator determines the amounts of fortifier and sweetener to add to a given wine to yield a fortified wine with the desired alcohol content, sugar content, and volume.  Alternatively, the resulting alcohol content, sugar content, and volume can be calculated from the specified fortifier and sweetener additions.  The sweetener can be either sugar, honey, or concentrate.

FermCalc offers three options for this calculation:

1. Specify target alcohol & sugar  >  Calculate fortifier/sweetener additions and volume – Specify the desired alcohol and sugar contents, and FermCalc will calculate the required additions of fortifier and sweetener to achieve the targets, as well as the resulting volume after the additions.
2. Specify target alcohol, sugar, & volume  >  Calculate fortifier/sweetener additions – Specify the desired alcohol content, sugar content, and volume, and FermCalc will calculate the required amounts of wine, fortifier, and sweetener to achieve all three targets.
3. Specify fortifier/sweetener additions  >  Calculate resulting alcohol, sugar & volume – Specify the amounts of fortifier and sweetener to be added, and FermCalc will calculate the resulting alcohol content, sugar content, and volume.

All volumes and specific gravities have a temperature basis of 20°C (68°F).  It is assumed that the fortifier contains only ethanol and water, and that the sweetener contains only sucrose and water.

For details regarding the mathematics involved in the calculations, see the calculation details pages at FermCalc.com.

Input Field Definitions

Sweetener – The type of sweetener to be added, either sugar, honey, or concentrate.  The SG of the sweetener must be specified if honey or concentrate is selected.

Fortifier Alcohol Content – The alcohol content of the fortifier being added.

Target Alcohol Content – The desired alcohol content of the fortified wine.

Target Sugar Content – The desired total solids content of the fortified wine.

Wine Volume – The volume of the wine prior to fortification.  Required only if either the first or third calculation option is selected.

Target Volume – The desired volume of the wine after fortification.  Required only if the second calculation option is selected.

Wine Alcohol Content – The original alcohol content of the wine being fortified.

Wine Sugar Content – The total solids content (true Brix) of the wine being fortified.

Fortifier Added – The amount of fortifier added to the wine.  Required only if the third calculation option is selected.

Sugar (or Honey or Concentrate) Added – The amount of sweetener added to the wine.  Required only if the third calculation option is selected.

Output Field Definitions

Fortifier Required – The calculated amount of fortifier required to yield the desired alcohol content, sugar content, and volume.  Reported only if either the first or second calculation option is selected.

Sugar (or Honey or Concentrate) Required – The calculated amount of sweetener required to yield the desired alcohol content, sugar content, and volume.  Reported only if either the first or second calculation option is selected.

Wine Required – The volume of wine required to yield the desired alcohol content, sugar content, and volume.  Reported only if the second calculation option is selected.

Resulting Volume – The calculated volume of the fortified win after adding the specified amounts of fortifier and sweetener.  Reported only if either the first or third calculation option is selected.

Resulting Alcohol Content – The alcohol content of the fortified wine after adding the specified amounts of fortifier and sweetener.  Reported only if the third calculation option is selected.

Resulting Sugar Content – The total solids content of the fortified wine after adding the specified amounts of fortifier and sweetener.  Reported only if the third calculation option is selected.

Resulting SG – The SG of the fortified wine after the addition of fortifier and/or sweetener.

The Fortification Point Calculator determines 1) the specific gravity (SG) at which to stop an active fermentation to yield the desired level of residual sugar in a fortified wine, and 2) the amount of fortifier required yield the desired alcohol level.  It accounts for the alcohol produced during fermentation, and for the dilution of the residual sugar by the addition of the fortifier.

After this "ideal" fortification point is calculated, the user has the option to override the calculated value of SG at the fortification point in order to model the impact of fortifying at a different SG.  If the entered SG is lower than the ideal value, then there is not enough residual sugar to achieve the target sugar content, so the sweetener addition required to achieve the target sugar content is calculated.  If the entered SG is higher than the ideal value, the sugar content will exceed the target sugar content after fortification, so the resulting sugar content after the addition of fortifier is calculated.

All volumes and specific gravities have a temperature basis of 20°C (68°F).  It is assumed that the fortifier contains only ethanol and water, and that the sweetener contains only sucrose and water.

For details regarding the mathematics involved in the calculations, see the calculation details pages at FermCalc.com.

Input Field Definitions

Sweetener – The type of sweetener to be added, either sugar, honey, or concentrate.  The SG of the sweetener must be specified if honey or concentrate is selected.  This is only used if the user enters a value of wine SG at fortification that is less than the "ideal" value, in which case the addition of a sweetener is required to achieve the target sugar content.

Fortifier Alcohol Content – The alcohol content of the fortifier being added.

Wine Volume – The volume of the fermenting wine at the time of fortification.  If this volume option is selected, the resulting volume after fortification is calculated.

Target Volume – The volume of the fortified wine after the addition of the calculated fortifier and sweetener additions.  If this volume option is selected, the required wine volume at the fortification point is calculated.

Initial Must SG – The SG of the must prior to the start of fermentation.

Target Alcohol Content – The desired alcohol content of the fortified wine.

Target Sugar Content – The desired total solids content of the fortified wine after the addition of fortifier and sweetener.

Wine SG at Fortification – The SG of the fermenting wine at the time of fortification.  This field can serve either as an input field or an output field.  Initially the "ideal" fortification point SG is calculated based on the inputs above.  If the calculated value is overridden by the user, then either the target sugar content or the required sweetener addition are calculated, depending on whether the entered SG value is greater than or less than the ideal value.

Output Field Definitions

Wine Alcohol Content – The calculated alcohol content of the fermenting wine at the fortification point.

Wine Sugar Content – The calculated total solids content (true Brix) of the fermenting wine at the fortification point.

Wine Required – The volume of fermenting wine required to yield the desired alcohol content, sugar content, and volume.  Reported only if target volume is selected as the volume option above.

Fortifier Required – The calculated amount of fortifier required to yield the desired alcohol content, sugar content, and volume.

Sugar (or Honey or Concentrate) Required – The calculated amount of sweetener required to yield the desired alcohol content, sugar content, and volume.  This will be zero unless the user enters a wine SG at fortification that is less than the "ideal" value.

Resulting Volume – The calculated volume of the fortified wine after adding the specified amounts of fortifier and sweetener.  Reported only if wine volume is selected as the volume option above.

Resulting SG – The SG of the fortified wine after the addition of fortifier and/or sweetener.

The Hackbarth SG Calculator utilizes the Hackbarth model to estimate SG from given values of alcohol content and sugar content.  Its purpose is mainly to validate the Hackbarth calculation in FermCalc, but it is also useful in the preparation of fortified wines and liqueurs.

For details regarding the mathematics involved in the calculations, see the calculation details pages at FermCalc.com.

Input Field Definitions

Alcohol Content – Alcohol content of the solution.  Range: 0% to 100% vol/vol.

Sugar Content – Sugar content of the solution.  Range: 0% to 100% by wt.

Output Field Definitions

Calculated SG – The calculated specific gravity (20°C/20°C) of the solution.

The Dry Weight/Volume Converter converts between dry weight (mass) and dry volume for a number of common winemaking additives.  This calculator is intended mainly for home winemakers who don't have accurate scales, and instead add ingredients on the basis of dry volumes (teaspoons, mL, etc.).

For details regarding the mathematics involved in the calculations, see the calculation details pages at FermCalc.com.

Input Field Definitions

Additive – The additive for which the conversion is being made.  Select from the long list of common (and not-so-common) additives.

Dry Weight – The dry weight (mass) of the additive.  This field can be either an input field or an output field.  If it is used as an input field, the dry volume is calculated from the entered value.

Dry Volume – The approximate dry volume of the additive.  This field can be either an input field or an output field.  If it is used as an input field, the dry weight (mass) is calculated from the entered value.

The Stock Solution Formulation Calculator determines the amount of an additive required to yield a stock solution with a given volume and concentration.

For details regarding the mathematics involved in the calculations, see the calculation details pages at FermCalc.com.

Input Field Definitions

Target Concentration – The desired concentration of the additive in the stock solution.

Solution Volume – The volume of the stock solution being made.

Output Field Definitions

Mass of Additive Required – The mass of the additive required to yield the desired concentration of the additive in the specified volume of stock solution.

The Inverse Stock Solution Makeup Calculator determines the amount of an additive required to yield a stock solution such that a specific volume of the solution will result in a desired increase in concentration of the additive in a specific volume of wine.

For details regarding the mathematics involved in the calculations, see the calculation details pages at FermCalc.com.

Input Field Definitions

Total Solution Volume – The total volume of the stock solution being made.

Wine Volume – The volume of wine being treated.

Volume of Solution Added – The volume of stock solution to be added to the wine.

Total Dosage – The desired increase in concentration of the additive in the given volume of wine.

Output Field Definitions

Mass of Additive Required – The mass of the additive required to make the given volume of stock solution.

The Miscellaneous Additions Calculator determines the amount of an additive to add to a wine to yield a desired concentration in the wine, given the initial concentration of the additive and volume of the wine. The additive can either be in the form of a solid (powder or crystals) or a liquid (stock solution).

For details regarding the mathematics involved in the calculations, see the calculation details pages at FermCalc.com.

Input Field Definitions

Additive Type – Select from either solid (powder/crystals) or liquid (stock solution).

Solution Concentration – The concentration of the additive in the stock solution being added.  Required only if liquid (stock solution) was selected as the additive type.

Target Concentration – The desired concentration of the additive.

Initial Concentration – The current concentration of the additive.

Wine Volume – The volume of the wine being treated.

Output Field Definitions

Mass of Additive Required – The mass of the additive required to yield the desired concentration in the specified volume of wine.  Reported only if solid (powder/crystals) was selected as the additive type.

Volume of Solution Required – The volume of stock solution required to yield the desired concentration in the specified volume of wine.  Reported only if liquid (stock solution) was selected as the additive type.

The Yeast Assimilable Nitrogen (YAN) Calculator determines the yeast nutrient additions required to supply the desired YAN level in a must.  The total YAN requirement is calculated based on the nitrogen requirements of the selected yeast strain and on the initial SG of the must.  The required masses of the selected nutrients are then calculated based on their nitrogen contents.  The additions can be scheduled in stages, with up to three nutrients added in up to four stages.

For details regarding the mathematics involved in the calculations, see the calculation details pages at FermCalc.com.

Input Field Definitions

Number of Nutrients – The number of yeast nutrients to be used over the course of the fermentation.  Up to three nutrients can be selected.

Number of Stages – The number of staged nutrient additions to be used.  Up to four stages can be used.

Yeast – The yeast strain to be used.  If your yeast strain is not listed, select from one of the three generic entries at the top of the list.

Nutrient (1, 2, 3) – The yeast nutrients to be used in the various stages.

Fermaid O Efficiency Factor – The organic nitrogen in Fermaid O is reportedly utilized by the yeast 3 to 4 times more efficiently than nitrogen in other nutrients.  This factor allows the user to account for this enhanced efficiency.  It is generally set to a value of 3, and is increased to a value of 4 if GoFerm is used during yeast rehydration.  Set it to a value of 1 if you want to ignore it.

Must Volume – The volume of the must being treated.

Must SG – The initial SG of the must being treated.  Range: 1.0 to 1.55454

Yeast Multiplier – The factor in mgN/g sugar that is multiplied by the sugar content of the must to calculate the total YAN required.  This is initially determined from the yeast strain selected above, but it can be overridden by the user.  A range is not enforced, but it should be in the range from 0.5 to 1.5.

Total YAN Required – The total YAN requirements over the course of the fermentation.  This is calculated based on the yeast strain and the must SG, but it can be overridden by the user.

Initial Must YAN Level – The estimated initial YAN concentration of the must, prior to the addition of any nutrients.  This needs to be estimated by the user.  Include here the contribution from any yeast rehydration nutrients.

Relative Mass or YAN Contribution at Each Stage – The relative mass or YAN contribution for each nutrient at each stage.  These values determine the mass or YAN allocation between the specified nutrients, as well as the allocation of each nutrient between the stages.  The proportional contribution for a given nutrient at a given stage will be the value entered in the corresponding field divided by the sum of the values in all of the fields.  These fields are required only if either the number of nutrients or the number of stages are greater than one.

Output Field Definitions

YAN Deficiency – The amount of YAN that needs to be supplied by the added nutrients, which is simply the difference between the total YAN required and the initial must YAN level.

Mass to Add – The mass of each nutrient at each stage needed to supply the total YAN requirements.

Addition Rate – The calculated mass per unit volume of each nutrient at each stage.  This allows the user to compare the calculated addition rates to those recommended by the manufacturer or to any legal maximums.

The settings panel allows you to set your default unit system, specific gravity (SG) units, acidity units, and temperatures.  It also allows you to reset all of the input values and units to their default values, and to adjust the font size if necessary.

Input Field Definitions

Unit System – The default unit system for all of the volume, mass, and temperature fields, with a few exceptions.  Exceptions include titration volumes in the acid calculators (since most burettes and syringes are metric), and concentrations in the miscellaneous additions calculators.  Select from English (US), English (UK), or Metric.

Hydrometer SG Units – The default SG units for the sugar, alcohol content, and fortification calculators.

Acidity Units – The default acidity units for the acid titration, acidification & deacidification, and amelioration calculators.

Default Temperature – The default SG reading temperature for the alcohol content calculators.  Range: 0°C (32°F) to 40°C (104°F)

Default Calibration Temperature – The default hydrometer calibration temperature for the alcohol content calculators.  Range: 0°C (32°F) to 40°C (104°F)

Font Size – The font size for all of the calculators.  The initial font size is set so the calculators fill the width of the screen (up to a maximum font size of 24px).

Auto-Select Contents of Input Fields – If checked, when the user clicks or taps on an input field, all the contents of that field will be automatically selected.  This option is enabled by default.  The auto-select feature can cause freeze-ups with the JavaScript app on some iOS devices, and disabling it is recommended if freeze-ups occur.  In this case, the user can double-click or double-tap in the input fields to select all the contents.

Button Definitions

Reset Default Values – Resets all input values to their original default values

Reset Default Units – Resets all of the unit selection dropdown boxes to their default selections for the unit system selected above.

Reset Size – Resets the font size to the automatically determined size that fills the width of the screen.

FermCalc® Winemaking Calculator v2.98.2
Copyright 2007-2023 Steve Gross.  All rights reserved.

By using FermCalc, you agree to this license agreement and to the FermCalc Privacy Policy.

FermCalc (the Software) is Freeware.  Steve Gross grants you (the licensee) permission to use the Software at no cost, both for commercial and non-commercial purposes, on any number of computers for as long as you like.

You may use and/or distribute the Software under the following conditions:

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• You understand and agree with this license and with the Disclaimer displayed below.
• Any redistribution must reproduce this license and the following Disclaimer in the documentation and/or other materials provided with the distribution.

THIS SOFTWARE IS PROVIDED BY STEVE GROSS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL STEVE GROSS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

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Steve Gross does not share customer or user lists, or any information regarding customers or users, with third parties.

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IF YOUR KEYPAD IS MISSING A DECIMAL...

On some Samsung and LGE devices, the stock numeric keypad lacks a decimal, which makes FermCalc nearly impossible to use.  If this is the case for your device, go to Google Play and install the Google Keyboard.  Then go to Settings > Language and Input, and set the Google Keyboard as your default keyboard.  This should resolve the missing decimal issue.

To read these instructions again, use the button at the bottom of the main help screen.