I realize that the IBU number itself is based on each brewery and a correlation to what the drinker perceives. My question pertains to calculation of that number.
When I calculate in BeerSmith I get a wildly different number that in Brewer’s Friend. I believe they both use Tinseth’s calculation but how are they 15 points apart? (I was not exact in my duplication but close enough to make the point):
Multiple things going on here:
1) Volumes -- This is the biggest one. Your first entry in Brewer's Friend says 6.5 gallons, versus BeerSmith says 5.5 gallons. That will have a huge effect.
2) Late hop additions in BeerSmith look way off to me. Should be much lower in single digits, not 10 IBUs each.
3) Are you really using whole hops? In Brewer's Friend you specify whole hops. Not sure about what you put into BeerSmith. But make sure those are consistent between the two softwares.
If whole hops and 6.5 gallons, I calculate about 26 IBUs. Otherwise.... well, it depends on all 3 of those things above.