IBU calculator off?

[Invader]

5.5 gal batch @ 2oz 4% hops is 19 IBU
35 gal batch (x6) is 56 oz! 3.75% for 18 ibu. Utilization is not THAT far off.

This is from building a 35 gal from scratch.

If I 'build' it as a 5.5 and scale up, it is 10 oz. This is more expected.

reference Hallertau Mittelfruh 3.75 is the hop in question.
Though, I recently had the issue of importing a beersmith recipe IBU of 109, and when I entered the hop bill it showed me 167 IBU in BF.

Something is amiss.

 

[Yooper]

Can I have a link to the recipe so I can check it out please?

 

[Invader]

Can I have a link to the recipe so I can check it out please?

https://www.brewersfriend.com/homebrew/recipe/view/1154131/bavarian-helles is the one 'built' at 35 gallons, showing 56 oz of hops for 18 IBU.

https://www.brewersfriend.com/homebrew/recipe/view/1154217/bavarian-helles-ii is the one 'built' at 5.5 gallons and scaled up to 35 showing ~10 oz for 19 IBU.

might have figured it out.

edit 2: figured it out.