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Homebrew calculator · OG & FG

ABV Calculator

The formula
ABV = (OG − FG) × 131.25
e.g. (1.050 − 1.010) = 5.25%

Plug in your original gravity and final gravity and this calculator estimates your alcohol by volume in seconds — the same formula homebrewers have used for decades.

Estimated alcohol by volume
5.3%
Formula: ABV = (OG − FG) × 131.25 · (1.0501.010) × 131.25

How to calculate alcohol by volume

Alcohol by volume (ABV) is the percentage of your finished beverage that is pure ethanol. Homebrewers and home winemakers estimate it from two density readings taken with a hydrometer. The first, original gravity (OG), measures how much sugar is dissolved in your liquid before the yeast goes to work. The second, final gravity (FG), is taken once fermentation stops. Yeast eat sugar and excrete ethanol, so the difference between the two numbers is a direct measure of how much alcohol was produced.

The formula ABV = (OG − FG) × 131.25 works because one gravity point is approximately 0.131% alcohol by volume in a typical beer. Take a pale ale that starts at 1.050 and finishes at 1.012: subtract to get 0.038, multiply by 131.25, and you land at about 4.99% ABV. The same math applies to wine, cider, and mead, though those beverages finish drier or sweeter depending on yeast and sugar levels.

If you do not brew yourself, you can still use the ABV numbers to compare what is in your glass — a 7% IPA has about 40% more alcohol than a 5% lager, which changes how fast you feel it. For the flip side of the equation, see how the cost calculator turns a daily habit into a yearly dollar figure.

Common beers and their ABV

BeerStyleABV
Miller LightLight lager4.2%
Coors LightLight lager4.2%
Bud LightLight lager4.2%
Guinness DraughtLager4.2%
BudweiserLager5.0%
HeinekenLager5.0%
Corona ExtraLager4.6%
Pilsner UrquellLager4.4%
Typical IPAIndia Pale Ale6.0–7.5%
Double / Imperial IPAIndia Pale Ale8.0–10%
Imperial StoutStout8.0–12%
BarleywineBarleywine9.0–12%

ABV figures are typical published values; exact numbers vary by batch, brewery, and vintage.

Reading gravity

Understanding OG and FG readings.

Two hydrometer readings are all you need to estimate ABV with the × 131.25 formula.

ScenarioOGFGABV
Light lager1.0401.0084.2%
Pale ale1.0501.0125.0%
IPA1.0621.0146.3%
Imperial stout1.0901.0248.7%

Higher original gravity means more sugar for the yeast, so stronger beers almost always start with a bigger OG. The FG depends on how fermentable the sugar is and how attentively the yeast works — a dry finish means the yeast ate almost everything, pushing FG down toward 1.006–1.010.

Your questions, answered

ABV calculator FAQ.

The questions homebrewers actually ask about estimating alcohol by volume.

Frequently asked questions

The standard homebrew formula is ABV = (OG − FG) × 131.25. Original gravity (OG) is measured before fermentation; final gravity (FG) is measured after. The difference tells you how much sugar the yeast converted into alcohol.
OG stands for original gravity — the density of your wort or must measured before fermentation begins, usually on a hydrometer reading like 1.050. It reflects the sugar content, so higher OG means more potential alcohol.
Most finished beers land between 1.008 and 1.016 final gravity. A very dry beer finishes near 1.006, while a sweet or heavy stout might finish at 1.020 or higher. Yeast strain and unfermentable sugars drive the exact number.
You can use a refractometer for the OG and FG readings of wort, but because alcohol skews the reading you need a correction formula or calculator for the FG. For most homebrewers, a hydrometer is the simplest, cheapest tool.
A standard lager like Budweiser or Miller Light sits around 4.2–5% ABV. IPA-style beers range from 6–7.5%, stouts often reach 8% or higher, and barleywines can hit 10–12%.
The × 131.25 multiplier is a linear approximation that works well for beers up to roughly 8% ABV. Above that, brewers use higher-order formulas like the Balling equation because the simple linear version starts to overestimate.

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Sourced fromCDC·WHO·NHS·American Lung Association