Homebrewing ABV Calculator
Estimate alcohol by volume, apparent attenuation, and gravity-point drop from original gravity and final gravity readings.
Last updated: 2026-03-27
Homebrewing ABV calculator
Enter your values
Enter your original and final gravity readings to estimate ABV and apparent attenuation.
Estimated ABV
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Enter the OG and FG readings from your batch to estimate alcohol and fermentation performance.
Calculation History(0)
Example calculations
Tap an example to prefill the calculator with sample values.
Session pale ale
1.048 OG down to 1.010 FG
A lighter-strength batch where a clean finish keeps the ABV modest but still clearly above a lawnmower lager.
Result: A crisp everyday-strength beer with healthy attenuation and a straightforward hydrometer story.
Classic IPA
1.062 OG down to 1.014 FG
A common homebrew-strength target where attenuation and ABV both land in a familiar craft-beer range.
Result: A standard-strength ale where the gravity drop translates to a solid mid-6% ABV result.
Big stout finish
1.090 OG down to 1.018 FG
A higher-gravity batch that still leaves more body behind, so the apparent attenuation matters as much as the ABV headline.
Result: The alcohol climbs quickly, but the fuller finish still shows up clearly in the attenuation result.
How the homebrew ABV estimate works
The calculator uses the standard quick brewing formula based on the difference between original gravity and final gravity. That gravity drop is the simplest practical signal for how much sugar was converted during fermentation.
It also calculates apparent attenuation so you can see not just how alcoholic the batch ended up, but how completely it fermented. That is often the more useful comparison point when you are evaluating yeast performance or recipe balance.
Homebrew ABV FAQs
Understand the OG/FG shortcut, why attenuation matters, and where the estimate stops being a lab result.
What do OG and FG mean in homebrewing?
Original gravity measures how much dissolved sugar is in the wort or must before fermentation, while final gravity measures how much remains after yeast has done its work. The drop between those readings is the main input for a quick ABV estimate.
Why is this an estimate instead of a lab measurement?
Because the quick ABV formula is a practical brewing shortcut built around hydrometer gravity readings, not a direct chemical measurement of ethanol. It is accurate enough for everyday batch evaluation, but it is still a brewing estimate.
What does attenuation tell me?
Apparent attenuation shows how much of the fermentable sugar appears to have been consumed. Brewers use it to understand how dry or full-bodied a batch finished and to compare yeast performance across recipes.
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</script> Related tools
Stay inside the fermentation workflow with nearby hobby and measurement tools.
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Brewing note
This ABV estimate assumes accurate, calibrated hydrometer readings and a finished fermentation. Refractometer-only workflows need correction before using this shortcut.