ABV Calculator
Alcohol by volume of beer, cider or mead from original and final gravity by the standard (OG - FG) x 131.25 formula, with the Hall 1995 alternate, the Balling/Plato cross-check, attenuation and calories.
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8 steps
- Standard: (OG - FG) x 131.25 = (1.05 - 1.01) x 131.25 = 0.04 x 131.25 = 5.25% ABV
- Hall 1995: ABW = 76.08 x 0.04 / (1.775 - 1.05) = 4.198% w/w; ABV = 4.198 x 1.01 / 0.794 = 5.339%
- Balling route (ASBC-table cubic fit, ethanol SG 0.7907): OE = 12.388 P, AE = 2.561 P
- q = 0.22 + 0.001 x 12.388 = 0.232388; real extract RE = (q x OE + AE) / (1 + q) = 4.414 P
- ABW = (OE - RE) / (2.0665 - 0.010665 x OE) = 7.9738 / 1.934386 = 4.122% w/w
- ABV = ABW x FG / 0.7907 = 5.265%
- Apparent attenuation = (OG - FG) / (OG - 1) = 0.04 / 0.05 = 80%; real attenuation = (OE - RE) / OE = 64.37%
- Calories per 12 oz (Hall) = 3.55 x 1.01 x (4.08 x 4.414 + 7.1 x 4.122) = 169.5 kcal
Its 5 worked examples are re-run on every release, last on 15 September 2026. What changed
Sources and references
8 sources
What this calculator does
Alcohol by volume of beer, cider or mead from original and final gravity by the standard (OG - FG) x 131.25 formula, with the Hall 1995 alternate, the Balling/Plato cross-check, attenuation and calories.
How to use ABV Calculator
Enter Gravity readings entered as, Original gravity (OG), before fermentation, Final gravity (FG), after fermentation, Plato conversion for the Balling cross-check, Correct hydrometer readings for temperature (approximate), Hydrometer calibration temperature, Temperature when OG was read and Temperature when FG was read. The calculator checks the values, applies the stated method, and updates the result without saving your figures.
What the result means
The result includes ABV, standard formula (OG - FG) x 131.25, ABV to the nearest 0.1% (label statement), ABV, Hall 1995 alternate formula, ABW, Hall 1995 alternate formula, ABV, Balling/Plato route (cross-check), ABW, Balling/Plato route, Apparent attenuation, Real attenuation, Original extract, Apparent extract, Real extract, Calories per 12 US fl oz (Hall), Gravity drop, OG used (specific gravity) and FG used (specific gravity). Review the visible working and any warnings before using the answer for a decision.
Method and checks
The method cites Grainfather Help Centre - Calculation: ABV (manufacturer); ABV = (OG - FG) x 131.25 with derivation and the 1.050 -> 1.010 = 5.25% example; Hall ML. Brew by the Numbers: Add Up What's in Your Beer. Zymurgy, Summer 1995;18(2) (scanned reproduction); The Brewers Journal - Science: Basic Beer Alcohol, extract determinations (Balling stoichiometry 2.0665 g sugar -> 1 g ethanol), among others. Its 5 built-in worked examples are checked on every full test run. The initial answer and working are rendered on the server, so they remain readable without JavaScript.
Results are general information, not financial, tax, legal, medical or engineering advice. Check any decision that matters with a qualified professional.
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