# IBU Calculator

International Bitterness Units (IBU) measure the concentration of isomerized alpha acids in beer, the compounds responsible for perceived bitterness. The Tinseth model calculates IBU from hop weight, alpha acid percentage, boil time, wort gravity and batch volume, with utilization rising steeply in the first 20 minutes and diminishing after that. Higher gravity wort reduces extraction.

Bitterness from one hop addition. Add up the additions in your recipe to get the total for the batch.

HTML version: https://brewgravity.com/calculators/ibu/

## Inputs

- **Hop weight (g)** (min 0, step 1) — default: 28
- **Alpha acid (%)** (min 0, step 0.1) — default: 12
- **Boil time (min)** (min 0, step 1) — default: 60
- **Boil gravity** (min 1, step 0.001) — default: 1.055
- **Batch volume (L)** (min 0.1, step 0.5) — default: 19
- **Hop form** (Pellet / Plug / Whole leaf) — default: pellet
- **Addition type** (Boil / First wort / Whirlpool at 85 °C / Dry hop) — default: boil

## Outputs

- **ibu**: IBU
- **util**: Utilisation

## FAQ

### Why does my calculated IBU not match my measured IBU?

Lab-measured IBU and calculated IBU routinely differ by 20% or more. Calculations assume complete, uniform extraction; real kettles have hop crowns, uneven boils and losses to trub. Use the number for comparison between your own recipes rather than as an absolute.

### How many IBU should my beer have?

It depends on the style and on the gravity. A helpful cross-check is the BU:GU ratio — IBU divided by gravity points. Around 0.5 is balanced, below 0.4 reads malty, above 0.8 reads bitter.

### Do dry hops add bitterness?

Not in the IBU sense — there is no boil, so almost no isomerisation. Heavily dry-hopped beers can taste sharper from hop polyphenols, but that will not show up in an IBU measurement or calculation.

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Source: https://brewgravity.com — Free Tinseth IBU calculator with the full utilisation formula, pellet/plug/leaf correction, whirlpool and first-wort handling, and an explanation of Tinseth versus Rager.