Hop Utilization

[Drunk Monkey]

I just bought the program last night and started entering in some of my old recipes. I seem to be missing some setting or something, because all my IBU readings are higher than they should be; my double IPA is around 250. Also, changing the amount of water in the 'Kettle Volume' has no effect on the final IBUs and I know this is a factor in hop utilization. Does BTP not account for this?

[just-cj]

In the session menu, there's a choice for utilization. Did you check to make sure the utilization formula is the same as what you originally used?

[pcharles]

In the session menu, there's a choice for utilization. Did you check to make sure the utilization formula is the same as what you originally used?

Yes, the basic does not have a gravity correction. I've started using the Rager formula because I heard about it on the Jamil Show Podcast. What I would like to do when I have time is take an average of all the different formulas to generate a custom set of formulas. Not sure if that is what the beer tools one is.

I am amazed how different the IBU results are from each formula.

[slothrob]

Some of the differences between the formulas is because the way they are calculated makes them more appropriate for different brewing techniques.

The frequently cited difference is the one between Rager and Tinseth. Tinseth takes into account the beginning gravity and ending gravity to determine a utilization that changes as the wort becomes more concentrated. This makes Tinseth good for full volume boils, but gives invalid results for partial volume boils that include a top-up step. Rager is more appropriate for partial volume boils.

Averaging the results from the two formulas would mean averaging one result that is appropriate for your brewing technique and one that isn't.