ABV calculator
Enter your original and final gravity to get your beer's alcohol by volume and apparent attenuation. Works for beer, cider and mead.
Alcohol by volume
Gravities in SG (1.050). The standard formula is accurate up to about 7–8 %; above that, the alternative formula is closer.
How ABV is calculated
The standard formula multiplies the gravity drop by 131.25: ABV = (OG − FG) × 131.25. The alternative formula, ABV = 76.08 × (OG − FG) / (1.775 − OG) × FG / 0.794, accounts for the density of alcohol and gives better results for strong beers. Apparent attenuation is (OG − FG) / (OG − 1): it tells you how much of the sugar your yeast has eaten.
Questions
Which formula should I use?
For most beers under 7 %, both give nearly the same result. For barley wines, imperial stouts and other strong beers, prefer the alternative formula.
My final gravity is a refractometer reading. Does that work?
Not directly: alcohol skews refractometer readings. Use our refractometer calculator to correct the final gravity first.
What attenuation should I expect?
Most ale yeasts reach 70–80 % apparent attenuation. If yours stopped well below the yeast's range, the fermentation may be stuck.
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