dbrewski
Well-Known Member
I know most people use Beersmith or some other software to develop recipes but I don't, I use an excel spreadsheet because it forces me to learn some things. One of those things are Tinseth's wonderful IBU equations. One of the key components of this calculation is the boil volume in gallons. Two others are boil time and boil gravity (to determine utilization).
All or most of the software I have checked use the batch size for boil volume. So for a 10.5 gallon batch, use 10.5 gallons. But it doesn't account for kettle losses. Let's say I leave .75 gallons in the kettle to keep trub and hops out of my fermenter. Doesn't that really make my end boil volume 11.25 gallons? I assumed yes...that if you end with 11.25 gallons of wort, that's what you should use, not the batch size of 10.5 just because you're throwing away .75G of it. However this results in a slightly lower (8%) IBU calculation compared with most software and even Glen's javascript calculator. It appears all of these use the batch size only.
Any thoughts on this? I kind of expect to hear crickets on this one, I should probably just accept it and move on.
All or most of the software I have checked use the batch size for boil volume. So for a 10.5 gallon batch, use 10.5 gallons. But it doesn't account for kettle losses. Let's say I leave .75 gallons in the kettle to keep trub and hops out of my fermenter. Doesn't that really make my end boil volume 11.25 gallons? I assumed yes...that if you end with 11.25 gallons of wort, that's what you should use, not the batch size of 10.5 just because you're throwing away .75G of it. However this results in a slightly lower (8%) IBU calculation compared with most software and even Glen's javascript calculator. It appears all of these use the batch size only.
Any thoughts on this? I kind of expect to hear crickets on this one, I should probably just accept it and move on.