Calculate beer, cider, or mead ABV from original gravity and final gravity, then estimate attenuation, packaged servings, standard drinks, and rough calories.
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ABV is estimated from the drop between original gravity and final gravity. This is the common homebrew formula for beer, cider, and mead planning.
ABV = (OG - FG) x 131.25Apparent attenuation compares gravity drop to the fermentable gravity above water. Batch gallons are converted to packaged servings and US standard drinks.
The Homebrew ABV Calculator scales ingredient quantities linearly by serving count or batch size. Non-linear items (yeast, salt, leavening) may use sub-linear scaling factors.
Scaled Amount = Base × (New Servings ÷ Original Servings)Updated: July 2026
Enter OG and FG after stable readings to estimate ABV before packaging.
Use apparent attenuation to see whether fermentation finished near the expected yeast range.
A host doubles or triples a favorite recipe using the Homebrew ABV Calculator so ingredient weights stay balanced for a larger batch.
Alcohol changes refractometer readings. Use a correction calculator or a hydrometer for final gravity.
Take stable readings over multiple days before bottling to reduce overcarbonation risk.
Turn hydrometer readings into a clear ABV estimate. Enter original gravity, final gravity, batch size, and package size to understand strength and yield.