I recently found that my calculations of IBUs are not always accurate... Especially when I was making a Braggot. Maybe someone can help me out with the formula or something?

I made a 5 gallon batch of IPA braggot.

I boiled 2.5 gallons of extract with a extract method (3lbs of extract, 12oz stepping grains, Hops at 60, 30, 15 and 1 mins).

At the end I blended it with a 2.5 gallons of mead must making total 5 gallons with OG=1.072. Not bad for an IPA. However, I'm not sure if it will be bitter enough...

So, here's a two batches:

1.   V = 2.5g,  OG = 1.048,  IBU = 158.
2.   V = 2.5g,  OG = 1.101,  IBU = 0.
1+2. V = 5g,    OG = 1.072,  IBU = ? 

What would the IBU be?

PS. Fermentation was complete yesterday at 1.014. I will dry-hop it with 3 oz of something citrusy and floral.


1 Answer 1


The alpha acids that give the bitterness from hops reach saturation somewhere around 90 IBUs. Since your hops were not exposed to the whole volume of beer (presumably they were filtered out at the of the boil) you aren't getting the full impact from them. It is reasonable to say that the IPA is actually 90 IBUs (saturation is around 90mg/L). Then divide by two for the addition of unhopped mead, leaving 45.

  • So, no matter how much hops I add for 2.5 gallon of wort, it will be always maxed out around 90-100IBU, right? So, if I want the whole thing to be around 60IBU, I should boil 4.5 Gallons of light wort (12oz stepping grains + 3lbv of LME) and add 7lb of honey at the flame out? I really don't want to boil honey (even though I've done it few times, and it didn't really impact the aroma dramatically). Should I boil 4-5lbv of honey and add the rest at flame out (2-3lbv)?
    – Trigger
    May 25, 2015 at 1:13
  • You can get isomerization above 170F, so it would be possible to bitter the mead without boiling. Also keep in mind the 90IBU thing says nothing about hop aroma, flavor, bitterness from tannins, etc
    – Pepi
    May 25, 2015 at 4:26
  • Great! I just found that one of my local stores (HopTech) sells variety of oils and extracts of different hops (including iso alpha extract). I can actually adjust my braggott to how I want... Bittering... taste... aroma... I had Sierra Nevada Summerfest IPL, and it was dryhopped with hop oils... It was awesome. So, there is hop(e). Thanks, Pepi. You've been helping me a lot lately.
    – Trigger
    May 25, 2015 at 7:55

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.