Hi Larry, I had a question about the IBU calculator. It says: For a 5.5 gallon batch, 7 gallons is typical boil volume for all grain, 3 for extract. Does that mean I should change the boil volume to 3 gallons (55% of batch size) for extract recipes?
If I have 6.25 gallons of boiling water and add 9 lbs LME, it comes to 7 gallons, and after 60 minutes of boiling and adding hops will come down to 5.5 gallons at 1.061 OG, so the boil size is technically 7 gallons. At a boil size of 7 gallons, adding 1 oz of 12% pellet hops each at 60, 20, 15, 10, and 5 calculates to 113 IBUs. If I keep boil and batch size both at 5.5 gallons, it calculates to 100 IBUs, but if I change the boil size to 3 gallons, it calculates to 63 IBUs. That really doesn't make sense. Why would extract have so much less hop utilization than all grain, after all isn't extract really all grain wort that someone else made and then packed and sold?
