Calculate ABV for beer, wine, or mead using original & final gravity
The core ABV relationship is straightforward: the more sugar yeast converts into ethanol and carbon dioxide, the bigger the gravity drop. Homebrewers usually track this with hydrometer or refractometer readings. The calculator supports both the standard linear model and a higher-precision model. The standard equation is perfect for most ales and lagers:
For stronger beers, mead, or high-attenuation fermentations, the alternate equation can reduce underestimation by accounting for density shifts more carefully. Either way, the critical habit is taking clean measurements. Degas your sample, correct for temperature when needed, and avoid reading from foamy liquid. Measurement quality matters more than choosing between two formulas that are already close.
Example workflow: you brew an IPA with OG 1.064 and FG 1.014. Standard ABV gives . If apparent attenuation lands around 78%, fermentation performed well for many American ale strains. That number also helps when deciding serving guidance: a 16 oz pour at 6.5% ABV delivers materially more alcohol than a 12 oz pour of a 4.5% session beer. For club competitions and style targets, this is often the difference between "on style" and "too hot."
Misconception #1: ABV alone defines flavor. It does not. Bitterness units, residual sweetness, water profile, and yeast-derived esters all shape perception. Misconception #2: FG only measures sugar left in solution. Alcohol lowers density, so apparent attenuation can look higher than real attenuation. Misconception #3: one reading is enough. Serious brewers check trends over a few days before packaging so they do not trap fermentable sugars in bottles or kegs.
Practical use cases include recipe iteration, packaging planning, and ingredient economics. If a batch repeatedly finishes higher than expected, the calculator helps isolate whether mash temperature, yeast health, or oxygenation is causing lower attenuation. If you distribute samples to friends or events, ABV also supports transparent labeling and safer consumption expectations. For commercial or semi-commercial use, always align with local labeling regulations, tax classification thresholds, and licensing requirements.
Keep this tool as part of a broader brew log: OG, FG, pitch rate, fermentation temperature, and tasting notes. Over multiple batches, you'll see stable fermentation fingerprints for each yeast strain and process setup. That historical context is what turns a one-time ABV estimate into repeatable brewing control.