Why is my actual FG lower than the recipe calculated?

Brewer #69764 · Aug 1, 2019

I brewed the NEIPA recipe linked below. Post-brew, I adjusted my efficiency so that calculated OG matched my actual OG. However, my actual FG is 1.009 instead of the calculated FG of 1.019. FWIW, this is the second time I've experienced a FG discrepancy for this recipe. Playing with the numbers on the recipe page, it seems like no adjustments (aside from changing the grains or grain amounts) can reduce the calculated FG. What could explain this discrepancy?

One final note, I've built and brewed many recipes on Brewers Friend and this is the first time I've had this issue with FG.

https://www.brewersfriend.com/homebrew/recipe/view/836389/tj-s-neipa

okoncentrerad · Aug 1, 2019

If I run this recipe through another software I get an estimated FG of 1.011.

GFHomebrew · Aug 1, 2019

Your yeast attenuation for that recipie is 65% I've never gotten a attenuation that low. Since you've brewed this twice now and know your yeast are attenuating more than recipie yeast attenuation setting you can adjust your yeasts custom attenuation in the yeast section in recipie calculator.

Brewer #69764 · Aug 3, 2019

Thanks to both of you! I thought I had adjusted the yeast attenuation with no effect on calculated FG. After a second look, I see that there are 3 places where it's possible to adjust attenuation. One has no effect on the calculation (and that box shows up only when you enter a yeast that's not already in the database) but as you point out the "custom attenuation" box does the trick. Solved!

Fleeulrich · Jan 10, 2020

Trialben said:
Your yeast attenuation for that recipie is 65% I've never gotten a attenuation that low. Since you've brewed this twice now and know your yeast are attenuating more than recipie yeast attenuation setting you can adjust your yeasts custom attenuation in the yeast section in recipie calculator.
View attachment 6775

That’s exactly what I was going to say. I make a yeast starter for almost every batch I brew especially if I am using liquid yeast. I end up usually 80% or higher for yeast attenuation. Brew On!