ABV Calculator
Work out the alcohol by volume of your beer, wine, or cider from hydrometer gravity readings, using both the quick and the more accurate formula. Shows attenuation too. Calculates in your browser.
Alcohol by volume
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Show the math
The quick estimate scales the gravity drop:
ABV ≈ (OG − FG) × 131.25
The alternate formula stays accurate for stronger brews:
ABV = (76.08 × (OG − FG) ÷ (1.775 − OG)) × (FG ÷ 0.794)
Gravity readings drift with temperature, so calibrate your hydrometer and read at its reference temperature for the best result. The two formulas agree closely at low strengths and diverge a little as the brew gets stronger.
What this does
An ABV calculator works out the alcohol by volume of beer, wine, or cider from hydrometer gravity readings, using both the quick and the more accurate formula, with attenuation.
How to use it
- Enter the original gravity.
- Enter the final gravity.
- Read the ABV from both formulas.
- See the apparent attenuation.
How it works
The quick estimate is close at low strengths; an alternate formula stays accurate for stronger brews. Attenuation is (OG − FG) ÷ (OG − 1).
ABV ≈ (OG − FG) × 131.25
Understanding your result
The ABV comes from how far the gravity fell during fermentation, so accurate original and final readings matter more than which formula you pick. The quick estimate is fine for everyday-strength brews; switch to the more accurate one for strong beers and wines, where the simple formula reads high.
Example
OG 1.050 and FG 1.010 gives an ABV of about 5.25%.
Sources & methodology
Last updated .
Frequently asked questions
How do I calculate ABV from gravity?
The quick estimate is (OG − FG) × 131.25, where OG is the original gravity and FG the final gravity. The tool also shows an alternate formula that stays accurate for stronger brews.
Why are there two ABV figures?
The simple formula is close at low strengths but drifts a little as a brew gets stronger. The alternate formula corrects for this, so the two diverge slightly for high-gravity beers and wines.
What is attenuation?
Apparent attenuation is the percentage of the sugars that fermented out, calculated as (OG − FG) ÷ (OG − 1). Higher attenuation means a drier, more fully fermented drink.
Is my data stored?
No. Everything is calculated locally in your browser.
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