ABV Calculator (Alcohol by Volume)
Enter your original gravity (OG) and final gravity (FG) readings to estimate the alcohol by volume of your homebrew, wine or cider.
How ABV is calculated
Alcohol by volume (ABV) in home brewing is estimated by comparing the specific gravity of your wort or must before fermentation (original gravity, OG) to the specific gravity after fermentation (final gravity, FG). Yeast converts sugar into alcohol, which lowers the density of the liquid, so the size of that drop tells you roughly how much alcohol was produced.
Standard vs advanced formula
The standard formula, ABV = (OG − FG) × 131.25, is simple and accurate enough for most beers and ciders. The advanced formula adjusts for the fact that alcohol itself is less dense than water, which makes it more accurate for higher-alcohol brews like strong ales, meads or wines.
- Standard: ABV% = (OG − FG) × 131.25
- Typical beer OG: 1.040–1.060, FG: 1.008–1.016
- Higher OG-to-FG drop generally means higher alcohol content
This tool is for general homebrewing and educational estimation only; it is not a substitute for a calibrated hydrometer, lab testing, or your local alcohol labeling regulations.