ABV Calculator

Calculate the alcohol by volume (ABV) of your beer, cider or mead from its original and final gravity.

Original gravity (SG)

Gravity before fermentation, e.g. 1.050

Final gravity (SG)

Gravity after fermentation, or your latest reading

Alcohol by volume5.25% ABV

Results are estimates provided "as is," for informational and planning purposes only, without warranties of any kind. Check them before you rely on them: you are responsible for decisions about your beer and equipment, including pressure and carbonation levels, the pressure ratings of your kegs and fittings, and any alcohol content you declare. Use of this calculator is subject to our Terms and Conditions.

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How ABV is calculated

Yeast turns sugar into alcohol and CO₂. Sugar makes wort denser than water, and alcohol is lighter than water, so the gravity falls as fermentation progresses. The size of that drop tells you how much alcohol was produced:

\text{ABV}\ (\%) = (\text{OG} - \text{FG}) \times 131.25

where OG is the original gravity and FG the final gravity.

For example, a beer that starts at 1.050 and finishes at 1.010 has dropped 0.040 points: 0.040 × 131.25 = 5.25% ABV.

Enter readings as specific gravity, such as 1.050. If you track a fermentation that is still running, use your latest reading as the final gravity to see the alcohol produced so far.

Inside Foambyte, ABV is calculated automatically from the gravity readings you log for each batch, together with the rest of your fermentation data.

Reference table

ABV (%) by original gravity (rows) and final gravity (columns)
OG \ FG	1.004	1.008	1.010	1.012	1.016	1.020
1.040	4.7	4.2	3.9	3.7	3.2	2.6
1.045	5.4	4.9	4.6	4.3	3.8	3.3
1.050	6.0	5.5	5.3	5.0	4.5	3.9
1.055	6.7	6.2	5.9	5.6	5.1	4.6
1.060	7.4	6.8	6.6	6.3	5.8	5.3
1.065	8.0	7.5	7.2	7.0	6.4	5.9
1.070	8.7	8.1	7.9	7.6	7.1	6.6
1.080	10.0	9.5	9.2	8.9	8.4	7.9
1.090	11.3	10.8	10.5	10.2	9.7	9.2
1.100	12.6	12.1	11.8	11.6	11.0	10.5

Frequently asked questions

How do I calculate ABV from gravity readings?

Subtract the final gravity from the original gravity and multiply by 131.25. For an original gravity of 1.050 and a final gravity of 1.010, the ABV is (1.050 − 1.010) × 131.25 = 5.25%.

When should I take the gravity readings?

Take the original gravity after the wort has cooled and before you pitch the yeast. Take the final gravity once fermentation has finished, when the reading stays the same over two or three days.

Does this ABV calculator work for cider and mead?

Yes. The calculation only uses the drop in gravity during fermentation, so it works the same way for cider and mead as for beer.

Can I use refractometer readings?

Only for the original gravity. Once fermentation starts, alcohol skews refractometer readings, so measure the final gravity with a hydrometer or correct the refractometer reading for alcohol first.

How accurate is this formula?

It is the standard formula used by most brewers and is accurate for typical beers. It slightly understates the ABV of very strong beers, where more complex formulas give a somewhat higher result.