Originally Posted by bsyoung
This might be a dumb question but why do different IBU calculators on the Internet give different values? Does anyone know a website that gives the most accurate calculation?
No, but if you find one let me know!
There are many reasons why they differ- some use different formulas (Rager, Tinseth), and some use different ways to figure the calculation. Some use wort gravity, some use boil size, some use only standard AAUs, etc.
The best advice I can give is to find one that seems to work for you, and stick with that one. I mean, 50 IBUs Tinseth in my system may taste remarkably like your 35 IBUs Rager in your system. But if it seems "right" to you, then use that scale for all of your batches to adjust, and forget others IBU ratings for different systems.
Also, look at the IBU/Sg ratio for a better idea of "bitterness" as a beer of an OG of 1.038 and 25 IBUs will be pretty bitter, but a beer with an OG of 1.080 and bittering of 25 IBUs will be underbittered and be sweet.