Alcohol By Volume Calculator

Work out alcohol by volume instantly with clear inputs, formula shown and shareable results.

About Alcohol By Volume Calculator

The standard homebrew formula is ABV = (original gravity - final gravity) x 131.25, and apparent attenuation is the share of the original gravity points that fermented out. Attenuation tells you whether a stuck fermentation is the reason a beer is sweet and low in alcohol, which gravity readings alone do not reveal.

Formulas

ABV

ABV % = (OG - FG) x 131.25

Attenuation

apparent attenuation % = (OG - FG) / (OG - 1) x 100

Worked example

With the default values below, Alcohol By Volume Calculator returns Alcohol by volume of 5.25%. Change any input above and every figure here is recalculated in your browser.

Inputs used

Original gravityaccepts 1–1.2: 1.05
Final gravityaccepts 0.98–1.2: 1.01

Results

Alcohol by volume: 5.25%
Alcohol by weight: 4.17%
Apparent attenuation: 80.0%
Approximate energy per litre: 334 kcal

Step by step

1Values used
2ABV
3Attenuation
4Alcohol by volume= 5.25
5Alcohol by weight= 4.17
6Apparent attenuation= 80.0
7Approximate energy per litre= 334 kcal

Assumptions and limits

The result is derived only from the 2 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

How is the Alcohol By Volume figure worked out?

ABV % = (OG - FG) x 131.25. The standard homebrew formula is ABV = (original gravity - final gravity) x 131.25, and apparent attenuation is the share of the original gravity points that fermented out.

Why does this matter?

Attenuation tells you whether a stuck fermentation is the reason a beer is sweet and low in alcohol, which gravity readings alone do not reveal.

What do I need to enter?

Enter original gravity, final gravity. The defaults shown are a realistic worked example — swap in your own figures to get a result you can use.