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IBU Calculator

Calculate International Bitterness Units for hop additions using the Tinseth method. Includes BU:GU balance ratio, utilization breakdown, hop stand and dry hop estimates, and BJCP style matching. For full multi-addition recipes, try the Build a Beer calculator.

Inputs

g
%
L

Volume of the boil (not final batch)

min

Specific gravity of the wort during the boil

Results

IBU

19.9 IBU

0–8
Berliner Weisse
8–15
Hefeweizen
15–20
Witbier
20–25
Kolsch
25–33
Amber Ale
33–40
Pilsner
5 more below
BU:GU 0.40 — this beer will taste malty/sweet
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Tips

1
Pellet hops get ~10% better utilization than whole leaf. The calculator adjusts for this.
2
Late additions (under 15 min) contribute more aroma than bitterness
3
For a balanced beer, aim for a BU:GU ratio between 0.5 and 0.8

Open formula

IBU = (W × A/100 × U × 1000) / V
Utilization:
U = bigness × time_factor × form_adj
bigness = 1.65 × 0.000125^(SG - 1)
time = (1 - e^(-0.04 × T)) / 4.15
Balance:
BU:GU = IBU / ((SG - 1) × 1000)

The Tinseth model calculates hop bitterness from weight, alpha acid %, and utilization, which depends on wort gravity and boil time. Higher gravity reduces utilization (sugar interferes with isomerization), while longer boils extract more alpha acids. BU:GU ratio measures bitterness relative to sweetness: below 0.5 is malty, 0.5-0.8 is balanced, above 0.8 is hop-forward.

Pellet hops gain ~10% utilization from their ruptured lupulin glands. First wort hopping adds ~10% from extended contact time. Hop stands contribute ~33% of boil-rate IBU at whirlpool temperatures.

Glenn Tinseth, 'Glenn's Hop Utilization Numbers' (1997). BU:GU ratio from Ray Daniels, 'Designing Great Beers'.

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