Homebrew ABV Calculator
Calculate alcohol by volume for homebrewed beer using original and final gravity readings. Enter values for instant results with step-by-step formulas.
Reviewed by Daniel Agrici, Founder & Lead Developer
Formula
ABV = (OG - FG) x 131.25
The standard formula multiplies the difference between Original Gravity and Final Gravity by 131.25. The alternate formula uses: ABV = (76.08 x (OG - FG) / (1.775 - OG)) x (FG / 0.794). Temperature correction adjusts readings calibrated at 60F.
Worked Examples
Example 1: Standard American Pale Ale
Problem:OG: 1.052, FG: 1.012, measured at 68F. 5-gallon batch. Calculate ABV and attenuation.
Solution:Temperature correction at 68F: +0.001\nCorrected OG: 1.053, Corrected FG: 1.013\nABV (standard): (1.053 - 1.013) x 131.25 = 5.25%\nApparent attenuation: (1.052 - 1.012) / (1.052 - 1) x 100 = 76.9%\nCalories per 12 oz: ~165\n12-oz beers: ~53
Result:ABV: 5.25% | Attenuation: 76.9% | ~165 cal/12oz | 53 beers per batch
Example 2: Imperial Stout
Problem:OG: 1.095, FG: 1.022, at 60F. 5-gallon batch. Compare standard vs alternate formula.
Solution:Standard formula: (1.095 - 1.022) x 131.25 = 9.58%\nAlternate formula: (76.08 x (0.073) / (1.775 - 1.095)) x (1.022 / 0.794) = 10.51%\nApparent attenuation: (0.073/0.095) x 100 = 76.8%\nThe alternate formula shows ~1% higher for this strong beer.
Result:Standard: 9.58% | Alternate: 10.51% | Attenuation: 76.8% | ~280 cal/12oz
Frequently Asked Questions
What is the difference between the standard and alternate ABV formulas?
The standard ABV formula, which multiplies the gravity drop by 131.25, is a simplified linear approximation that works well for beers under 6 percent ABV. It assumes a constant relationship between gravity change and alcohol production, which is reasonably accurate for most homebrews. The alternate formula, sometimes called the more accurate or advanced formula, accounts for the nonlinear relationship between gravity and alcohol at higher concentrations. It uses a more complex calculation that factors in the specific gravity of alcohol relative to water. For very strong beers above 8 percent ABV, the alternate formula can be 0.5 to 1 percent more accurate than the standard formula.
How do I estimate calories in my homebrew?
Beer calories come from two sources: alcohol and residual carbohydrates. Alcohol contributes about 7 calories per gram and carbohydrates about 4 calories per gram. The formula uses ABW (alcohol by weight), final gravity in Plato, and the final gravity value to calculate total calories per 12-ounce serving. A typical light beer has 100 to 120 calories per 12 ounces. A standard pale ale has 150 to 180 calories. An IPA ranges from 180 to 250 calories. Strong beers like imperial stouts and barleywines can exceed 300 calories per 12 ounces. Knowing the calorie content of your homebrew helps with dietary awareness, especially since craft beer calories are not displayed on labels.
References
Reviewed by Daniel Agrici, Founder & Lead Developer · Editorial policy