ABV Calculator
Use entered original and final specific gravity to estimate alcohol by volume and apparent attenuation with one fixed home-brewing approximation. This page covers “abv calculator”.
How to use the ABV Calculator
Enter original specific gravity and a final specific gravity no greater than the original value.
Review hydrometer calibration, temperature correction, dissolved gas, refractometer alcohol correction, fermentation completion, and method range.
Read estimated alcohol by volume and apparent attenuation percentages.
Formula
Estimated ABV% = (original gravity − final gravity) × 131.25. Apparent attenuation% = (original gravity − final gravity) ÷ (original gravity − 1) × 100.
Example
Original gravity 1.050 and final gravity 1.010 give estimated ABV (1.050 − 1.010) × 131.25 = 5.25%.
Assumptions and limitations
- The result is a fermentation estimate, not a certified laboratory measurement or legal label determination.
- ABV Calculator treats the entered values as estimates and does not infer missing project, account, or personal details.
- Calculations retain working precision except where the cited method requires an intermediate rounding step; displayed values are then formatted separately. Source rules and dated rates must be rechecked when they change.
Sources
- Alcohol and Tobacco Tax and Trade Bureau: Beverage Alcohol LaboratoryOfficial beverage-alcohol measurement and laboratory context. Reviewed 2026-08-14.
- Journal of Chemical Education: A Hands-On Guide to Brewing and Analyzing Beer in the LaboratoryThe empirical ABV = (OG − FG) × 131.25 estimate and its gravity inputs. Reviewed 2026-08-14.
- National Institute of Standards and Technology: How Do You Measure the Percentage of Alcohol in Beverages?Official formula, rate, or program guidance used by this calculator. Reviewed 2026-08-14.
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Frequently asked questions
How does the ABV Calculator work?
Estimated ABV% = (original gravity − final gravity) × 131.25. Apparent attenuation% = (original gravity − final gravity) ÷ (original gravity − 1) × 100.
What information should I enter in the ABV Calculator?
Enter original specific gravity and a final specific gravity no greater than the original value, then verify hydrometer calibration, temperature correction, dissolved gas, refractometer alcohol correction, fermentation completion, and method range.
What should I verify before using this ABV Calculator result?
The result is a fermentation estimate, not a certified laboratory measurement or legal label determination.
Reviewed 2026-08-14 · og-fg-linear-131.25-1.0.0 · content-2026-08-14 · Trusty Calculator Editorial Team