Your Beer Attenuation & ABV Calculator: Brewing Math Made Simple
Whether this is your first batch or your fiftieth, figuring out how your beer turned out is one of the most satisfying parts of the process. That’s exactly what this little calculator is for. Just punch in two numbers—your original gravity and your final gravity—and it’ll do the rest.
Original gravity (OG) is the reading you take before fermentation starts. It’s basically a snapshot of how much sugar is sitting in your wort, waiting for the yeast to get to work. Final gravity (FG) is the reading you take once fermentation has wrapped up. The difference between those two numbers tells the story of what the yeast actually ate.
From that difference, the calculator figures out two useful things. First is apparent attenuation, which is the percentage of available sugars the yeast converted. A higher number usually means a drier beer; a lower number points toward something a bit fuller and sweeter. Second is the estimated alcohol by volume (ABV). That’s the percentage of alcohol in the finished beer, the number most of us are curious about when we crack open a bottle.
Using the tool is straightforward. Enter your OG and FG (in specific gravity units, like 1.052 or 1.010), hit calculate, and you’ll get both the attenuation percentage and the ABV. No complicated formulas to remember, no spreadsheets are required. Just two numbers in, useful info out.
Yeast Attenuation & Alcohol Calculator
A couple of quick tips to keep things accurate: try to take both gravity readings at roughly the same temperature. And remember that these are estimates—real-world factors like residual sugars, yeast health, and even the specific gravity of any added water or fruit can nudge the numbers a little. Still, for homebrew purposes, the results are plenty close enough to know what you’re drinking and how the fermentation performed.
This calculator is here to take the guesswork out of those final numbers so you can focus on the fun parts: tasting, tweaking recipes, and sharing your beer with friends. Drop in your readings, see what you get, and keep brewing. Cheers to another successful batch!
Disclosure: The calculators on this site are provided for informational and educational purposes only. They are intended as general aids for homebrewing and are not guaranteed to be accurate. Results can vary based on equipment, ingredients, conditions, and technique. Use of these tools is at your own risk.