Quick Question on calculating IBU

[atromic]

If I am doing a large partial mash, how do I calculate IBU if I'm using a late extract addition?

If I'm using beersmith, should I calculate it based on my boil volume, and only the gravity from the 8.5 lbs of mashed grains? I typically mash my grains, sparge up to 4 gal, then add all my LME at flameout.

I'm shooting for around 60 IBU, but beersmith ranges from 57-80 depending on how I set up the recipe.

 

[jkarp]

Contrary to what the software's telling you, newer science has proven that wort gravity doesn't have a significant influence on hop utilization; especially with extract. Besides, it's highly unlikely you'd be able to tell the difference in taste between 57 and 60, or even 80 IBUs.

 

[atromic]

Cool, good to know. Thanks for the quick reply.