The most recent formula was derived by Cutaia, Reid and Speers in 2009. You can monitor this change to find the alcohol content of your homebrew.Īll formulas for finding the ABV are approximate, as they are found empirically rather than derived. When fermentation occurs, the specific gravity of the liquid changes. Specific gravity is the relative density of a liquid compared with the density of water. The standard method of estimating ABV is to use the specific gravity. Alex Speers in the Journal of the Institute of Brewing. The actual calculation is a bit more complex and is described in the paper: Examination of the Relationships Between Original, Real and Apparent Extracts, and Alcohol in Pilot Plant and Commercially Produced Beers published by Anthony J.

Most calculators use a simplified formula for calculation of ABV which is (OG - FG) * 131.25 = %ABV. Online calculators (standard equation) ABV: 9.58% (one of the calculators differs by 0.02%)Įven the 'alternate' method that some calculators offer are still different from BS3. Online calculators (standard equation) ABV: 7.88% (one of the calculators differs by 0.02%) To give some real data here are two calculations from some recent beers: So that begs two questions which is correct, BS3 or all of the other calculators? And why are the calculations different? So I've been brewing with BS3 for a little while now (my exact version is 3.0.8 for Windows) but I've never actually double checked their ABV calculations against other calculators, which seems odd now that I think of it.īut I've just done some comparisons with a beer I'm currently fermenting and I've realised that both the estimated ABV from the recipe screen and the calculated ABV from the 'Alcohol and Attenuation' tool give out a different value to every other calculator I can find online:

I know there a lot of posts about ABV calculation on here but none of them appear to be the same issue I'm having.

Beersmith 3 actual alcohol