Hop Bitterness IBU (Tinseth)
Computes IBU from alpha acids, boil time, and wort gravity by Tinseth's utilization.
Example
You enter
- Batch volume (gal) 310
- Hop addition (lb) 5
- Alpha acid (%) 12
- Boil time (min) 60
- Wort gravity during the boil 1.05
- Shorter boil to compare (min) 15
- Stronger wort to compare 1.08
You get
- Alpha acids in the wort 231.9 mg/L
- Utilization 0.230664
- Bitterness 53.5 IBU at 23.1% utilization
- At the shorter boil 26.5449
- In the stronger wort 40.9 IBU -- 24% lost to gravity alone
- Hops to hold the bitterness 6.55 lb in the stronger wort
Checked against published worked examples from: John Palmer.
Details, formula, and sources
ScopeThe worked 5 lb of 12% hops in 310 gal gives 53.5 IBU at 23% utilization. A quarter of the boil gives half the bitterness, and the same hops in 1.080 wort give 40.9 IBU -- a strong beer needs 6.5 lb to taste the same.
Formula or tableIBU = alpha acids (mg/L) x 1.65 x 0.000125^(SG - 1) x (1 - e^(-0.04 t)) / 4.15.
Source and editionTinseth's empirical utilization fit. The brewery's own measured IBU (ASBC Beer-23) on its own system governs.
Free accessTinseth's relation is published openly.
What governsEstimate. AHJ and licensed professional govern.
API field namesbatch_volume_gal, hop_weight_lb, alpha_acid_pct, boil_minutes, boil_gravity, short_boil_minutes, strong_boil_gravity, alpha_acid_mg_per_l, utilization, ibu, short_boil_ibu, strong_gravity_ibu, hops_to_match_lb
- Fit an empirical fit to measured beers; whirlpool and late additions are not modelledTinseth