ABV calculator
Enter your original and final gravity, get the alcohol by volume.
How do you calculate ABV from original and final gravity?
The usual homebrew formula is ABV = (OG − FG) × 131.25. For an original gravity of 1.050 and a final gravity of 1.010 that is 0.040 × 131.25 = 5.25% alcohol by volume. Take OG with your hydrometer before you add the yeast and FG when the gravity stops dropping.
What is the difference between the standard formula and the Hall formula?
Brew Your Own prints ABW = 76.08 × (OG − FG) ÷ (1.775 − OG) and ABV = ABW × FG ÷ 0.794, where 0.794 is the specific gravity of ethanol. It is a simplified form of the Balling calculation in Michael Hall’s 1995 Zymurgy article “Brew by the Numbers”. Below about 6% ABV the two formulas agree closely; at higher gravity the Hall formula gives the higher number. For OG 1.092 and FG 1.021 the standard formula gives 9.32% and the Hall formula 10.17% (Brewer’s Friend). Here, at OG 1.100 and FG 1.020, they give 10.5% and 11.6%, and the Balling method 10.7%.
Which formula is most accurate?
None of them measures alcohol — a laboratory distills the beer and weighs it. All three are estimates built on Carl Balling’s 19th-century tables. The Balling method on this page converts both readings to degrees Plato first; across OG 1.030–1.100 and FG 1.000–1.030 it stayed within 0.3 percentage points of the standard formula. The same gravity readings can be entered for cider, mead or wine, but the formulas were built for beer wort, so treat very sweet musts as rougher.
How do I correct a hydrometer reading for temperature?
Hydrometers are usually calibrated at 60 °F (15 °C) or 68 °F (20 °C), and a warm sample reads lower than it really is. Brew Your Own gives a polynomial correction valid from 32 to 212 °F: a reading of 1.046 at 75 °F on a hydrometer calibrated at 60 °F becomes 1.0477. Use the Temperature tab and pick your hydrometer’s calibration temperature.
What do attenuation and the calorie count mean?
Apparent attenuation is the share of the gravity points the yeast used up: (OG − FG) ÷ (OG − 1), 75% for 1.048 to 1.012. Calories use the ASBC formula from The Oxford Companion to Beer: 6.9 × alcohol by weight plus 4 × (real extract − ash) per 100 g of beer, with ash taken as 0.1 (Palmer), then multiplied by the beer’s density and by 3.55 for 12 fl oz. It is an estimate; labels on commercial beer come from lab analysis.
To turn the ABV into drinks, use the standard drink calculator. A refractometer reading of unfermented wort is in °Brix, practically the same scale as °Plato for sugar solutions, but it reads wort high (Palmer: about 96% of the Brix value is Plato), and alcohol changes what a refractometer reads once fermentation starts — so this page takes hydrometer readings only.
Sources: Brew Your Own, “Calculating Alcohol Content, Attenuation, Extract, and Calories” (Bill Pierce); Brewer’s Friend, “Alcohol By Volume Calculator Updated” (Hall, Zymurgy 1995; Daniels, Designing Great Beers); The Oxford Companion to Beer, “calories” (Gary Spedding); John Palmer, “Beer Math” (How to Brew). How we check our calculators.