ABV Calculator for Homebrew (Beer, Wine, Cider)
Alcohol content of a home-brewed beer, wine or cider from its original and final gravity readings, with the attenuation and original extract.
Results
The dashed line marks the value you entered.
What this tool does
Yeast turns sugar into alcohol and carbon dioxide, and because alcohol is lighter than water the gravity falls as fermentation goes on: the drop between the two hydrometer readings is a measure of the alcohol made. The everyday formula multiplies it by 131.25 and is good for normal-strength beers; the second formula keeps its accuracy for strong beers and wines, where the two start to differ. Correct the readings to the hydrometer's calibration temperature first, and remember a refractometer reading after fermentation needs its own correction for alcohol.
Formula
ABV ≈ (OG − FG) × 131.25 · ABV ≈ 76.08 (OG − FG) ÷ (1.775 − OG) × FG ÷ 0.794
Variables
| Symbol | Meaning | Unit |
|---|---|---|
og | Original gravity (OG) | — |
fg | Final gravity (FG) | — |
AB | Alcohol by volume (standard formula) | % |
AA | Alcohol by volume (formula for strong beers and wines) | % |
AT | Apparent attenuation | % |
PL | Original extract | °P |
Worked example
- Original gravity (OG)1.05
- Final gravity (FG)1.01
- Alcohol by volume (standard formula)5.25 %
- Alcohol by volume (formula for strong beers and wines)5.34 %
- Apparent attenuation80.0 %
- Original extract12.39 °P
Limitations
- The result is an estimate based only on the values you type. Real situations often include factors this calculator does not know about.
- The default values are typical reference figures, not measurements of your situation. Replace them with your own data whenever you have it.