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.

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...

But 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:

https://www.brewersfriend.com/abv-calculator/

https://homebrewsupply.com/abv-calculator/

https://www.hopsteiner.com/abv-calculator/

https://www.morebeer.com/content/abv_calculator

So that begs two questions;

**which is correct, BS3 or all of the other calculators? And why are the calculations different?**

To give some real data here are two calculations from some recent beers:

**Beer #1**OG 1.077

FG 1.017

BS3 ABV: 8.2%

Online calculators (standard equation) ABV: 7.88% (one of the calculators differs by 0.02%)

**Beer #2**OG 1.102

FG 1.029

BS3 ABV: 9.9%

Online calculators (standard equation) ABV: 9.58% (one of the calculators differs by 0.02%)

Even the "alternate" method that some calculators offer are still different from BS3.