Calculator
IBU Calculator
Add each hop with its weight, alpha acids and boil time, and it gives you the recipe's IBU and which styles it fits.
IBU Calculator: how to use it
- Enter the liters (or gallons) left at the end of the boil and the gravity of the wort in the boil (the OG works).
- Add one line for each hop addition: grams (or ounces), % alpha acids (it's on the package) and boil minutes.
- Hops added at flameout or as a dry hop barely add bitterness: enter them with 0 minutes or leave them out.
How it works
Bitterness comes from the alpha acids in hops, which only become soluble when boiled: the longer they boil, the more bitter the beer, up to a ceiling around 60–90 minutes. The Tinseth formula estimates how much of those alpha acids ends up in the beer based on boil time and wort gravity (denser wort gets less out of the hops). It's the most widely used formula in homebrew recipes. Keep in mind that alpha acids vary from one harvest to the next: always use the percentage printed on your package.
Frequently asked questions
How many IBU does a typical beer have?
A commercial lager is around 10 IBU, a pale ale 30–50, and an American IPA goes over 40. Above 100 your palate can barely tell the difference.
Do pellet hops add more bitterness than whole-cone hops?
Somewhat more, around 10%, because they're used more efficiently. The calculator doesn't correct for it: if you use whole cones, expect a little less bitterness.
How long should I boil bittering hops?
About 60 minutes. Past that point they add very little extra bitterness, and what you add in the last few minutes contributes mostly flavor and aroma.
Does dry hopping add bitterness?
Hardly any: without boiling, the alpha acids barely dissolve. Hops in the fermenter give aroma, not bitterness.