Alcohol By Volume (ABV) Calculator
Homebrewers calculate alcohol by volume (ABV) by measuring the specific gravity of their wort before fermentation (original gravity, OG) and after fermentation is complete (final gravity, FG). Specific gravity measures the density of liquid relative to water (which has a gravity of 1.000). Fermentable sugars make the wort denser than water, so OG is typically 1.040 to 1.080. As yeast consumes those sugars and converts them to alcohol and carbon dioxide, density decreases. The difference between OG and FG reflects how much sugar was fermented. The standard simplified ABV formula is: ABV = (OG - FG) x 131.25. This is accurate to within about 0.1% for standard-strength beers. This calculator also estimates calories per 12 oz serving (using a standard approximation combining alcohol and residual carbohydrate calories) and the number of US standard drinks per 12 oz serving, where one standard drink equals 14 grams of pure alcohol as defined by the National Institute on Alcohol Abuse and Alcoholism (NIAAA).
ABV by beer style reference
| Style | Typical OG | Typical FG | ABV range |
|---|---|---|---|
| Light lager | 1.028 to 1.040 | 1.006 to 1.010 | 2.8% to 4.4% |
| American ale | 1.040 to 1.060 | 1.008 to 1.014 | 3.9% to 6.8% |
| IPA | 1.056 to 1.070 | 1.010 to 1.014 | 5.5% to 7.9% |
| Porter / stout | 1.060 to 1.080 | 1.014 to 1.020 | 5.2% to 8.7% |
| Barleywine | 1.080 to 1.120 | 1.016 to 1.030 | 6.6% to 13.7% |
ABV calculator: frequently asked questions
What is the formula for calculating ABV from gravity?
The standard simplified formula used by homebrewers is: ABV = (OG - FG) * 131.25, where OG is original gravity and FG is final gravity. For example, an OG of 1.050 and FG of 1.010 gives (1.050 - 1.010) * 131.25 = 5.25% ABV. This formula is accurate to within about 0.1% for standard beers with ABV below 10%.
What is a standard drink?
In the United States, a standard drink contains 14 grams of pure alcohol. This equals approximately 12 fluid ounces of regular beer at 5% ABV, 5 fluid ounces of wine at 12% ABV, or 1.5 fluid ounces of 80-proof distilled spirits at 40% ABV. The National Institute on Alcohol Abuse and Alcoholism (NIAAA) uses this definition for dietary guidelines and health recommendations.
What original gravity readings are typical for beer?
Typical original gravity ranges by beer style: light lagers 1.028 to 1.040; standard ales 1.040 to 1.060; porters and stouts 1.060 to 1.080; barleywines and imperial stouts 1.080 to 1.120 or higher. Higher OG means more fermentable sugars and a higher potential ABV.
What final gravity should I expect?
Final gravity depends on the yeast strain and the amount of unfermentable sugars (dextrins) in the wort. Most beer yeasts attenuate (ferment) 70% to 80% of available sugars. A wort starting at 1.050 will typically finish between 1.008 and 1.014. Very dry beers (high attenuation) finish lower; sweeter, fuller-bodied beers finish higher.
How many calories are in a 12 oz beer?
Beer calories come from two sources: alcohol and residual carbohydrates. Alcohol contributes approximately 7 calories per gram. The formula used here is: calories per 12 oz = ((0.53 * ABV) + (0.1 * (FG - 1) * 1000)) * 355. A 5% ABV beer with FG of 1.010 has approximately 150 to 160 calories per 12 oz serving.
References
- National Institute on Alcohol Abuse and Alcoholism: What is a standard drink?
- Dietary Guidelines for Americans 2020-2025: dietaryguidelines.gov.
Reviewed by the CalculatorHub team, edited by James Graham, 14 June 2026. See our methodology.