ABV Calculator
Calculate alcohol by volume from your hydrometer readings. Enter your Original Gravity (OG) and Final Gravity (FG) to get started.
Gravity Readings
How ABV Is Calculated
Alcohol By Volume (ABV) measures the percentage of alcohol in your finished beer, wine, or mead. It's determined by comparing your wort's gravity before fermentation (Original Gravity) to the gravity after fermentation (Final Gravity).
The Simple Formula
The most widely used formula among homebrewers:
ABV = (OG - FG) × 131.25
This formula works well for beers under 6% ABV. It was popularized by Charlie Papazian and remains the standard quick calculation.
The Alternate (More Accurate) Formula
For higher-gravity beers, this formula provides better accuracy:
ABV = (76.08 × (OG - FG) / (1.775 - OG)) × (FG / 0.794)
This accounts for the non-linear relationship between gravity and alcohol content at higher concentrations. It's recommended for imperial stouts, barleywines, and other high-ABV styles.
Attenuation
Apparent Attenuation measures how much of the original gravity the yeast appeared to consume. Most yeast strains have an apparent attenuation range of 65-85%.
Real Attenuation accounts for the fact that alcohol is lighter than water. It corrects the apparent reading using the real extract formula, and is typically about 15-20% lower than apparent attenuation.
Calorie Estimation
Beer calories come from two sources: alcohol and residual carbohydrates. Our calculator uses the formula derived by the USDA, factoring in both the caloric content of ethanol (7 cal/g) and residual sugars (4 cal/g) to estimate calories per 12-ounce serving.
Tips for Accurate Readings
- Always calibrate your hydrometer at the specified temperature (usually 60°F / 15.6°C)
- Take multiple readings and average them
- If using a refractometer for FG, remember to apply the alcohol correction factor
- Wait until fermentation is truly complete before taking your final gravity reading