Janets Brown IBU adjustments

So I'm gonna brew Janets Brown Ale in the next few days and need to make some hop adjustments. The Northern Brewer i have is 10.5% AA and the recipe in Brewing Classic Styles is formulated to 6.5%. I put the recipe into Beersmith and tried to adjust the hops, but before adjusting them my recipe (according to Beersmith) is only 3 IBUs off? Not sure how this can be possible with such a difference in AA content. I dialed the hop AAs to what BCS has (6.5%) and those didn't match either. Not sure how to make adjustment if the software isn't calculating right.

Do i need to change something in my software? should I just say f$*% it and brew the same recipe with 10.5% Alpha hops?

tried changing the bitterness formula in Beersmith, but the IBUs are still way off from whats in BCS

I'm brewing this recipe this weekend too, and have been searching but not found a good answer. Tasty uses Promash and that doesn't match Beersmith for whatever reason. So I'm going to keep the mash hop and 15 & 0 min hop the same and adjust the the 60

I did this recipe about 3 weeks ago and recall that I had a similar issue. The recipe is based on the Ranger scale and once I changed it in beersmith I was just about right on.

Ive brewed it twice now.

Don't worry about the IBU's. The mash hops throw off different software.

I like to double dry hop it. Man I love that beer!

Jammim, what sort of fermentation schedule do you use? I'm thinking of dry hopping in the primary for a week beginning at the end of week three. Then I'll cold crash and keg and hope to be drinking on Christmas day.

I fermented for 10 days - then dry hopped for 10 days. I crashed for 2 days after that as I used Denny's 1450 yeast (its slow to floc).

I am finishing up the dry hop on a batch right now but with PacMan this time. The samples are much chocolatier with this batch so far. Probably won't cold crash this one as pacman seems to floc pretty well.

I think your plan should work out really well! You're gonna love it - such a great beer.

Drinkn on my freshly kegged JBA. Cold crashing and boost carbing got it from grain to glass in 19 days. I give most of the credit to a healthy pitch of PacMan and temp control. PacMan really pushes the chocolate malt forward in this recipe. Double dry hops rock too!

To the OP, make sure your software is set to Rager & not Tinseth for calculating IBUs.

Edit: oops, nevermind, just saw your second post!

When I'm replicating someone else's recipes, I just use the old school AAU method.

6.5% x 2oz = 13 AAUs
13AAU / 10.5% = 1.24oz

(I was just making up the weights here - don't have the recipe in front of me)

differences in Estimated Pre-Boil Vol on design page might be causing it

larger boil size increases hop utilization & will bump up the IBUs in the Style Guide Comparison