CalculateGravity-based estimate
ABV Calculator
Free ABV calculator: enter your original and final gravity to get alcohol by volume (ABV) and apparent attenuation for your homebrew.
Calculate alcohol by volume (ABV) from your original and final gravity readings.
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How the ABV Calculator works
Alcohol by volume (ABV) measures how much of your finished beer is alcohol. It is derived from the drop in density as yeast ferments sugar: the further the gravity falls from the original (OG) to the final (FG) reading, the more alcohol was produced.
The standard homebrew estimate multiplies the gravity drop by 131.25, which is accurate for typical strengths. For high-OG beers we also show the Hall alternate formula, which corrects for the non-linearity at higher gravities.
Frequently asked questions
- What is the ABV formula?
- The common homebrew formula is ABV = (OG − FG) × 131.25, where OG and FG are specific gravity readings.
- Why does my ABV differ from another calculator?
- Different calculators use different constants (131.25 vs the more accurate cubic Hall formula). For strong beers the alternate formula reads slightly higher.
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