How is ABV calculated?

The standard formula is ABV = (OG - FG) x 131.25. This uses the difference between original and final gravity to estimate alcohol content. The alternate formula (ABV = (76.08 x (OG - FG) / (1.775 - OG)) x (FG / 0.794)) is more accurate for higher-gravity beers.

What is a typical OG for beer?

Most ales have an OG between 1.040 and 1.060. Session beers may start as low as 1.030, while strong ales, barley wines and imperial stouts can reach 1.090 or higher.

What should the final gravity be?

Final gravity depends on the beer style and yeast attenuation. Most beers finish between 1.006 and 1.016. A very dry beer may finish at 1.002, while a sweet stout might end at 1.020.

Which ABV formula should I use?

The standard formula (OG - FG) x 131.25 works well for most homebrews under about 6% ABV. For stronger beers above 8%, the alternate formula gives a more accurate result as it accounts for the density change caused by higher alcohol content.

Why is my ABV different from expected?

ABV can differ from targets due to incomplete fermentation (stuck fermentation), inaccurate gravity readings from temperature differences, or yeast with different attenuation than expected. Always temperature-correct your hydrometer readings.

ABV Calculator — Free Gravity & ABV Tool

How We Calculate This

The Standard ABV Formula

The most commonly used formula is: ABV = (OG - FG) x 131.25. This works by measuring the drop in specific gravity as sugars are consumed by yeast and converted to alcohol and CO2. Since alcohol is lighter than water, the gravity drops as fermentation progresses.

The Alternate Formula

For beers above ~8% ABV, the alternate formula provides better accuracy: ABV = (76.08 x (OG - FG) / (1.775 - OG)) x (FG / 0.794). This accounts for the non-linear relationship between gravity drop and alcohol content at higher concentrations.

Taking Accurate Readings

Use a hydrometer calibrated at 20°C (68°F) and correct for temperature differences. Take OG after the boil and cooling, before pitching yeast. Take FG when gravity has been stable for 2-3 consecutive days.

Frequently Asked Questions

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Last updated: 2025-02-20

All calculations are estimates. Always verify values and adjust based on your equipment and ingredients.

ABV Calculator — Alcohol By Volume