Author Topic: Conflicting IBU calculations?  (Read 2313 times)

Offline dipso123

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Conflicting IBU calculations?
« on: March 25, 2018, 01:30:59 PM »
I am seeing a lot of disparity in IBU calculations within BeerSmith. I am assuming user error but cannot seem to figure out what I need to change. Any ideas would be greatly appreciated.

I was unsure of what to enter for SG in Hop Bitterness Tool so I entered the Est Pre-boil, but even when I change it to the Est OG it still is nowhere close to the recipe page calculation - as you can imagine the Tool numbers go down as the SG increases.

Thanks!

The recipe page calculates 57.5 IBUs and the Hop Bitterness Tool calculations are: Rager = 41.1, Tinseth = 40, Garetz = 22.






Offline jomebrew

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Re: Conflicting IBU calculations?
« Reply #1 on: March 25, 2018, 03:50:17 PM »
When I put your hops in, I get different numbers. I get 43.7 IBU.  When I change the batch volume to 6G, I get 40 IBU.

Comparing the tool to my recipe, I get 69.1 in the tool and 67.2 in my IPA recipe.    Adjusting my batch size to 5G adjust the recipe bitterness to match the tools calculation.

I tweaked numbers and found trub loss affects estimated IBU as does BH Efficiency.  A bit of trial and error, it seems the tool assume an efficiency of 60%.  The higher your efficiency, the lower the IBU.  Since my efficiency is 63.1%, my calculated IBU is a little lower

Offline dipso123

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Re: Conflicting IBU calculations?
« Reply #2 on: March 25, 2018, 04:42:13 PM »
Thanks -- this makes sense and I'll fool around with these variables.

 

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