Gravity & ABV Calculator

How It Works

ABV is calculated using the difference between original gravity (before fermentation) and final gravity (after fermentation). The standard formula ABV = (OG - FG) x 131.25 works well for most beers. For high-gravity beers above 6% ABV, the alternate formula provides more accurate results by accounting for the non-linear relationship between gravity and alcohol content. Apparent attenuation tells you what percentage of sugars the yeast consumed, with typical values ranging from 65-85%. Real attenuation is lower because alcohol is lighter than water, making the hydrometer read lower than the actual remaining sugar.