ABV Calculator — Homebrew Alcohol Content

How ABV is calculated

The calculator uses the common formula (OG − FG) × 131.25 / 1000, where OG is the gravity of the wort before fermentation and FG is the gravity after it. Measure both with a hydrometer.

For example, if OG is 1.050 and FG is 1.010, the difference is 40 points and the result is roughly 5.3 % ABV.

What you enter and what you get

Enter the original gravity (OG), the final gravity (FG) and the batch size in litres. From these the calculator derives every result.

You get alcohol by volume (ABV), alcohol by weight (ABW), the attenuation and an estimate of how many standard drinks the batch contains.

What attenuation tells you

Attenuation shows how much of the sugar in the wort was converted into alcohol during fermentation. A high attenuation means a drier, stronger finished drink.

A low final gravity relative to the original gravity indicates a more complete fermentation.

Measuring tips

Read the hydrometer at eye level and account for temperature correction, since measurement accuracy directly affects the result. Record OG just before pitching the yeast and FG only once fermentation has stopped.