ABV Calculator

Hydrometer readings are specific gravity. A "1050"-style entry is accepted as 1.050. Refractometer Brix on fermenting beer needs an alcohol correction and must not be used as FG.
Degas the sample first - CO2 bubbles lift the hydrometer.
Only affects the Balling/Plato route, extract figures and calories. The two cubics differ by about 0.01 P over normal wort gravities.
Printed on the hydrometer.
ABV, standard formula (OG - FG) x 131.25
5.25 %
Alcohol by Volume (ABV) Calculator
ABV to the nearest 0.1% (label statement)
5.3 %
ABV, Hall 1995 alternate formula
5.34 %
ABW, Hall 1995 alternate formula
4.20 % w/w
ABV, Balling/Plato route (cross-check)
5.27 %
ABW, Balling/Plato route
4.12 % w/w
Apparent attenuation
80.00 %
Real attenuation
64.37 %
Original extract
12.39 P
Apparent extract
2.56 P
Real extract
4.41 P
Calories per 12 US fl oz (Hall)
169.5 kcal
Gravity drop
40.0 points
OG used (specific gravity)
1.0500
FG used (specific gravity)
1.0100
Worked out from Grainfather Help Centre - Calculation: ABV (manufacturer); ABV = (OG - FG) x 131.25 with derivation and the 1.050 -> 1.010 = 5.25% example and 7 other sources.
A gravity-derived ABV is an estimate, not an analytical determination. 27 CFR 7.65 requires label statements to the nearest 0.1% and permits a +-0.3 point tolerance on malt beverages of 0.5% ABV or more.
The Balling-route cubic and the 0.7907 ethanol divisor are the figures used throughout the brewing literature but were not verified against ASBC's member-only tables; the Hall 1995 coefficients are verified from the article.

How this is worked out

8 steps
  1. Standard: (OG - FG) x 131.25 = (1.05 - 1.01) x 131.25 = 0.04 x 131.25 = 5.25% ABV
  2. 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%
  3. Balling route (ASBC-table cubic fit, ethanol SG 0.7907): OE = 12.388 P, AE = 2.561 P
  4. q = 0.22 + 0.001 x 12.388 = 0.232388; real extract RE = (q x OE + AE) / (1 + q) = 4.414 P
  5. ABW = (OE - RE) / (2.0665 - 0.010665 x OE) = 7.9738 / 1.934386 = 4.122% w/w
  6. ABV = ABW x FG / 0.7907 = 5.265%
  7. Apparent attenuation = (OG - FG) / (OG - 1) = 0.04 / 0.05 = 80%; real attenuation = (OE - RE) / OE = 64.37%
  8. Calories per 12 oz (Hall) = 3.55 x 1.01 x (4.08 x 4.414 + 7.1 x 4.122) = 169.5 kcal

Results are general information, not financial, tax, legal, medical or engineering advice.