ABV Calculator

The standard homebrewing formula is ABV = (OG − FG) × 131.25, where OG is your original gravity (measured before fermentation) and FG is your final gravity (measured after fermentation completes). The difference between the two reflects how much sugar was converted to alcohol.

The standard formula, (OG − FG) × 131.25, is accurate to within about ±0.3% for most beers with an original gravity up to 1.070. For higher-gravity beers, meads, or wines, the advanced formula — 76.08 × (OG − FG) / (1.775 − OG) × (FG / 0.794) — is more accurate since it accounts for how alcohol's lower density skews the gravity reading at higher concentrations.

You need to measure OG with a hydrometer or refractometer before fermentation starts — there's no way to calculate ABV after the fact without it, since ABV depends on the total sugar that was available for the yeast to ferment.

Yes — hydrometers are typically calibrated for a specific temperature (often 60°F/15.6°C or 68°F/20°C). If your sample is significantly warmer or cooler than the calibration temperature, you should apply a temperature correction before using the reading here.