I've been using This picture from beersmith.com of a refractometer (Looks like the same refractometer as mine) scale to go back-and-forth between my brew notes (at the computer) when doing ABV calculations. I sometimes record the SG reading during the brew because I'll have the target OG of the recipe in mind and just not "thinking" in Brix.

Today, I noticed the scale at beersmith and the one in my refractometer (pic below) are not the same! Shouldn't both just be representative of the mathematical equations to convert Brix <> Wort SG @ 20C?

Other than a crummy QC process at the factory, is there another reason these two scales would be so wildly different (eg: compare at 16 Brix and then again at 29 Brix)?

My scale

  • Might be due to point #2 from here perhaps? homebrew.stackexchange.com/a/10916/18441 I have seen this mentioned elsewhere too, but I'm far from an expert. Aug 26, 2020 at 15:52
  • Aha.. that must be it: "...equation to convert from degrees Brix to specific gravity that was incorrectly published on byo.com. ". According to this calculator, I've got an accurate scale (brewersfriend.com/brix-converter) at least..as long as their calculator isn't based on the bad formula. If you want to post your comment as an answer I can give you the internet points for it ;)
    – HomeBrew
    Aug 26, 2020 at 17:34

1 Answer 1


Simple. The SG scale is wrong. Only use Brix. A refractometer is incapable of measuring SG. It's an approximation, and in this case especially, it's pretty far off.

Instead of using that SG scale, use a conversion tool like this, which is way more accurate when done properly, both for OG and FG:



Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.