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Generated on: July 20, 2026 at 09:33 PM

ABV Calculator

Inputs

FormulaStandard
Original gravity1.05
Final gravity1.01

ABV figures are estimates based on gravity readings and standard conversion constants. Actual strength varies with fermentation conditions, ingredients, and hydrometer accuracy. Do not rely on these figures for labelling, sale, or any use where a legally certified measurement is required.

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Lifestyle

ABV Calculator

Estimate the alcohol by volume (ABV) of home-brewed beer, wine, mead, or cider from the original gravity and final gravity measured with a hydrometer. The standard estimate uses ABV% = (OG − FG) × 131.25; a precise mode tracks higher-strength brews more closely.

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Inputs

1 – 1.2
0.9 – 1.2

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%

How it is calculated

\begin{aligned} A &= (OG - FG) \times 131.25 \\ &= (1.05 - 1.01) \times 131.25 \\ &= ? \end{aligned}

A drop from 1.05 to 1.01 gives about ... alcohol by volume.

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ABV

Alcohol by volume (ABV) is the share of a drink that is pure ethanol, given as a percentage of the total volume. For a home-brewed beer, wine, mead, or cider the alcohol is produced by yeast fermenting sugar, so the finished strength can be estimated from how far the sugar concentration fell during fermentation. That concentration is measured as specific gravity with a hydrometer.

The gravity method

A hydrometer reports specific gravity relative to water, which reads 1.000. Dissolved sugar makes the liquid denser, so an unfermented wort reads above 1.000 — a typical beer sits near 1.050. As yeast converts the sugar to alcohol, which is lighter than water, the gravity falls. The gap between the starting reading, the original gravity (OG), and the finishing reading, the final gravity (FG), is proportional to the alcohol produced.

The standard formula

The estimate printed on most brewing charts multiplies the gravity drop by a fixed constant:

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

The constant 131.25 folds together the density of ethanol and the sugar-to-alcohol conversion. It is accurate for beers up to roughly 6–7% ABV, which covers the great majority of homebrew.

The precise formula

At higher gravities the relationship between the gravity drop and the alcohol produced is no longer linear, and the standard formula drifts low. The precise mode uses an alternate that corrects for this:

ABV%=76.08 (OG−FG)1.775−OG×FG0.794\text{ABV\%} = \frac{76.08 \, (OG - FG)}{1.775 - OG} \times \frac{FG}{0.794}

For strong beers, wines, and meads this tends to be the better match. For an ordinary-strength beer the two formulas agree within a few tenths of a percent.

Worked example

Suppose a pale ale starts at an original gravity of 1.050 and finishes at a final gravity of 1.010. Using the standard formula:

ABV%=(OG−FG)×131.25=(1.050−1.010)×131.25=0.040×131.25=5.25%\begin{aligned} \text{ABV\%} &= (OG - FG) \times 131.25 \\ &= (1.050 - 1.010) \times 131.25 \\ &= 0.040 \times 131.25 \\ &= 5.25\% \end{aligned}

The precise formula gives a slightly higher figure for the same readings:

ABV%=76.08×0.0401.775−1.050×1.0100.794=3.0430.725×1.272=5.34%\begin{aligned} \text{ABV\%} &= \frac{76.08 \times 0.040}{1.775 - 1.050} \times \frac{1.010}{0.794} \\ &= \frac{3.043}{0.725} \times 1.272 \\ &= 5.34\% \end{aligned}

At this strength the difference is small, so the standard 5.25% is a reasonable answer for a beer of this kind.

Getting accurate readings

Take the OG reading after mixing the wort or must but before pitching the yeast, and take the FG reading only once the gravity has held steady for a few days — a still-falling reading means fermentation is not finished. Read the scale at the bottom of the meniscus and spin the hydrometer to shake off clinging bubbles.

Hydrometers are calibrated to a reference temperature, commonly 20°C. A sample that is much warmer or cooler than that needs a temperature correction before the reading is used, otherwise the density and therefore the ABV estimate will be off.

For related drink and kitchen estimates, see the calculators below, including the Standard Drinks & Alcohol Units Calculator for turning an ABV figure into standard drinks.

Frequently Asked Questions (FAQ)

What is alcohol by volume?

Alcohol by volume (ABV) is the fraction of a drink that is pure ethanol, expressed as a percentage of the total liquid volume. A beer at 5% ABV contains 5 millilitres of pure alcohol in every 100 millilitres.

For a fermented drink the alcohol comes from yeast converting sugar into ethanol, so ABV can be estimated from how much the sugar concentration — measured as specific gravity — fell during fermentation.

What is the difference between original gravity and final gravity?

Original gravity (OG) is the specific gravity of the unfermented wort or must, measured before the yeast is added. It reflects the amount of dissolved sugar, so a higher OG means more sugar available to ferment.

Final gravity (FG) is measured once fermentation is complete. Because sugar has been converted to alcohol, which is lighter than water, the gravity drops. The size of the drop from OG to FG is what the ABV estimate is based on.

Which formula should I use?

The standard estimate, ABV% = (OG − FG) × 131.25, is the figure most brewing charts print and is accurate for beers up to roughly 6–7% ABV.

The precise mode uses (76.08 × (OG − FG) / (1.775 − OG)) × (FG / 0.794), which corrects for the non-linear relationship between gravity drop and alcohol at higher strengths. For strong beers, wines, and meads the precise result tends to be a better match.

How do I read a hydrometer?

Float the hydrometer in a sample of the liquid and read the scale where the surface crosses it, at the bottom of the meniscus. Give it a gentle spin to shake off bubbles first.

Hydrometers are usually calibrated to a set temperature, often 20°C. If your sample is much warmer or cooler, a temperature-correction adjustment keeps the reading accurate. Take the OG reading before pitching yeast and the FG reading once the gravity has held steady for a few days.

Disclaimer

ABV figures are estimates based on gravity readings and standard conversion constants. Actual strength varies with fermentation conditions, ingredients, and hydrometer accuracy. Do not rely on these figures for labelling, sale, or any use where a legally certified measurement is required.

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