ABV Calculator
Calculate alcohol by volume (ABV) for homebrewing from gravity readings.
Assumptions used in this calculation
- Simplified formula: Uses the standard simplified ABV formula (OG − FG) × 131.25, not the more precise gravity-corrected formula used for high-gravity brews above ~10% ABV.
About this calculator
Homebrewers track fermentation progress with a hydrometer, but converting the before-and-after specific gravity readings into an actual alcohol percentage requires a formula most people don't carry around, and getting it wrong can mean mislabeling a batch's strength. This calculator takes your original gravity (OG, measured before fermentation) and final gravity (FG, measured once fermentation has stabilized) and applies the standard simplified formula ABV% = (OG − FG) × 131.25, which is accurate for most beers up to roughly 10% ABV. It doesn't apply the more complex gravity-corrected formula used for high-gravity beers and wines above that range, where the relationship between gravity drop and alcohol content becomes less linear, so very strong brews may see the true ABV run half a percent or more higher than this simplified estimate shows. Rather than looking up and manually working through the formula on a calculator each time you take a reading, this gives an instant, accurate ABV estimate for typical-strength homebrew straight from your two gravity readings.
Worked example
OG 1.050, FG 1.010
Result: 5.25% ABV
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