On my last brew I compared that calculator with http://www.tastybrew.com/calculators/. I like the first calc better, but I found that tastybrew's is more accurate. Not sure if the ingredient values were slightly off or if they're using a different equation (someone always uses .129 vs .131 or something like that). The tastybrew guy said they were willing to make more calculators if you threw them ideas and responded very quickly to me. Actually I wish there was even a better interface. Maybe one of these days I'll build a better one :) if there is ever that time.