Beer ABV Calculator
Calculate ABV from original and final gravity readings for homebrewing. Compare alcohol content across popular beer styles.
⚠️ Educational Tool Only — Never Drink and Drive
This calculator is for educational purposes only and provides estimates based on averages. Actual BAC depends on many individual factors. Never rely on a calculator to determine if you are safe to drive. If in doubt, don't drive. Call a rideshare, taxi, or designated driver.
How It Works
The ABV is calculated from the original gravity (OG, before fermentation) and final gravity (FG, after fermentation) using the standard formula: ABV = (OG - FG) × 131.25. A more accurate alternate formula is: ABV = (76.08 × (OG - FG) / (1.775 - OG)) × (FG / 0.794). The OG measures sugars before yeast converts them to alcohol and CO2. The FG measures remaining sugars. The difference represents how much sugar was fermented into alcohol.
Frequently Asked Questions
What is a good original gravity for beer?
It depends on the style. Light beers: 1.030-1.040. Pale ales: 1.045-1.060. IPAs: 1.060-1.075. Stouts: 1.050-1.075. Barleywine: 1.080-1.120. Higher OG means more potential alcohol.
What does final gravity tell you?
Final gravity (FG) indicates how much sugar remains after fermentation. A lower FG means more sugar was converted to alcohol (drier beer). Most beers finish between 1.005 and 1.015. A high FG may indicate stuck fermentation.
How do I measure gravity?
Use a hydrometer (floats in a sample of beer) or a digital refractometer. Take the OG reading after mashing and boiling but before adding yeast. Take the FG reading when fermentation is complete (stable reading over 2-3 days).