Brewfather - Hop Stand IBU Calculations

[IrondaleBrewing]

I was plugging the Dark Ale recipe (https://www.homebrewersassociation.org/homebrew-recipe/the-empire-strikes-back-dark-ale/) for Big Brew Day into Brewfather, and the IBUs are way off according to Brewfather -- recipe estimates about 75, Brewfather says about 120. The hop stand step in particular seems to send it through the roof.

Is this a Brewfather quirk or is the recipe off? Ignore it and brew on?

Thanks for any insights!

 

[kurds_2408]

So I just added a 1.5oz hop stand of Citra for 20min at 194 degrees (what the recipe calls for) to one of my brown ales in BrewFather and it only added 18.4 IBUs. What is yours showing?

 

[kurds_2408]

Well curiosity got the best of me so I entered the whole recipe in Brewfather. What batch size are you doing? Leaving my equipment at 5.5g batch size I got 90 IBUs. If I bump it up to the 6g batch size the recipe is for I get 86. So a little higher than what they say. I'm guessing if you follow the recipe instructions and bag the boil hops, then pull them all out before the hopstand, that would somewhat reduce your IBUs. Brewfather wouldn't account for that, but maybe the recipe does account for it so that would explain my 11 extra IBUs.

 

[dmtaylor]

Brewfather is typically really bad at predicting IBUs for whatever reason. You might be interested in downloading this and giving it a try (yes I'm a little biased but aiming for accuracy AND simplicity). It can also be memorized to help you estimate IBUs on the fly using just a regular calculator.

Taylor IBU Calculator

 

[IrondaleBrewing]

So I just added a 1.5oz hop stand of Citra for 20min at 194 degrees (what the recipe calls for) to one of my brown ales in BrewFather and it only added 18.4 IBUs. What is yours showing?

Mine's 15.2 but based on the next post in this thread I think I see where I'm going wrong ...

 

[IrondaleBrewing]

Well curiosity got the best of me so I entered the whole recipe in Brewfather. What batch size are you doing? Leaving my equipment at 5.5g batch size I got 90 IBUs. If I bump it up to the 6g batch size the recipe is for I get 86. So a little higher than what they say. I'm guessing if you follow the recipe instructions and bag the boil hops, then pull them all out before the hopstand, that would somewhat reduce your IBUs. Brewfather wouldn't account for that, but maybe the recipe does account for it so that would explain my 11 extra IBUs.

Ah HA! Thank you. Original recipe is for SIX gallons, not 5. Oversight on my part and that explains it. I mean it's still a bit higher with the right batch size, but not 50% higher. Thanks for pointing out the batch size!

 

[IrondaleBrewing]

Brewfather is typically really bad at predicting IBUs for whatever reason. You might be interested in downloading this and giving it a try (yes I'm a little biased but aiming for accuracy AND simplicity). It can also be memorized to help you estimate IBUs on the fly using just a regular calculator.

Taylor IBU Calculator

Thanks, I'll check that out!