I just lead a "Learn to Homebrew Day" brew, using a Brewers Best Kit for an American Pale Ale, simple, right?
Well, the bitter wort tasted rather extremely bitter for that style, and the directions say O.G. = 1.051 to 1.055, 32 to 36 IBU, which seems lightly bitter, so I put the orginal gravity and hopping schedule into my spread sheet, which uses the Pyle's Hops FAQ, 5/4/95 Rager formulas. See; http://realbeer.com/hops/FAQ.html
With O.G. = 1.054, 2 oz. of 6.9% AA Cascade at 60 min., and 1 oz. of 12.5% AA Citra at 5 min. left, I get 80 IBU. Hmm, about what it tastes like, a very bitter IPA, although before fermentation it's hard to tell much by taste.
So I went to http://www.brewersfriend.com/ibu-calculator/
and it says 60 IBU, using Tinseth's equations.
Beersmith says 105 IBU.
Brew 365, http://www.brew365.com/ibu_calculator.php
says 60 by Tinseth, 57 by Rager.
Tasty Brew, http://www.tastybrew.com/calculators/bitterness.html
says 57 IBU by Tinseth.
My old Rager calculation from Pyle's Hops FAQ, 5/4/95 is what I’ve been using for nearly 20 years, and it’s 80 IBU is in the middle, but what a range! Amazing. I know IBU calculation is rough, and not very accurate, but the results here are all over the map. I'd expect the Rager from all sources should be within a couple points at most. Any idea what's up here? I think I entered the date correctly in all cases. Thanks!