I just started doing forced fermentation (FF) tests with each batch I make. I know that the final gravity of the FF beer will be lower than the final gravity of the beer fermented normally in the carboy -- but how much lower? Is there a normal range, or is it going to vary wildly?

For example, I just finished a batch of ESB. The FF beer has an FG of 1.013 and the beer in the carboy stopped at 1.016 - 1.017. Is that a normal range, or is that an indication that the beer in the carboy didn't ferment fully?

  • 1
    1.013 AND 1.016 probably are not actually statistically different when you factor in the accuracy of your measurement tools.
    – brewchez
    Jan 10, 2011 at 12:42
  • I'm not familiar with the term "forced fermentation" (I've heard of forced carbonation). Can you clarify for noobs like me? Jan 10, 2011 at 20:59
  • winning-homebrew.com/forced-fermentation-test.html Has a bit more description. Basically you take a small amount (I use 500 mL) of your post-boil wort and ferment it warm, using constant aeration to encourage active fermenting. It's a way to test the fermentability of your wort. If your normally-fermented beer finishes way higher than the FF test, then you may be doing something wrong with your fermentation -- underpitching, under-aeration, etc.
    – Hopwise
    Jan 10, 2011 at 21:28

1 Answer 1


Nope, there is no "normal" range. That's why you do the test! In your example, you simply show that your beer could have fermented further. different styles will have different limits and how closely you approach those limits of tied to the style.

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