# ABV Calculator

Alcohol by volume (ABV) is the percentage of a beer's volume that is ethanol, calculated from the drop in specific gravity during fermentation. The standard estimate is ABV = (OG − FG) × 131.25, accurate below about 1.070. For stronger worts, ABV = 76.08 × (OG − FG) / (1.775 − OG) × (FG / 0.794) corrects for the density shift ethanol introduces.

Enter the original gravity you measured before pitching and the final gravity after fermentation. Everything else follows from those two numbers.

HTML version: https://brewgravity.com/calculators/abv/

## Inputs

- **Original gravity (OG)** (min 1, step 0.001) — default: 1.055
- **Final gravity (FG)** (min 0.98, step 0.001) — default: 1.012

## Outputs

- **abv**: ABV
- **abw**: ABW
- **att**: Apparent attenuation
- **cal**: Calories / 12 oz

## FAQ

### What is a normal final gravity?

For most ales, 1.008 to 1.016. It depends on the yeast's attenuation and how fermentable the wort is — a mash at 62 °C produces a much more fermentable wort than one at 70 °C, so the same recipe can finish several points apart.

### Why is my ABV lower than expected?

Usually the fermentation stalled or the mash was less fermentable than planned. Check the final gravity against the yeast's stated attenuation: if the yeast claims 75% and you got 65%, the beer has stopped early rather than the calculation being wrong.

### Which ABV formula is correct?

Both are approximations of the same thing. The simple (OG − FG) × 131.25 form is fine below about 1.070; above that the alternative formula used here tracks reality more closely.

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Source: https://brewgravity.com — Free ABV calculator using OG and FG, with the alternative high-gravity formula, plus ABW, apparent attenuation and calories, and a worked table of typical gravity pairs.