IBU Calculator

Calculate International Bitterness Units for your beer recipe. Input hop variety, alpha acid percentage, weight, boil time, and batch volume to compute IBU contributions using the Tinseth formula. Compare total bitterness against BJCP style guidelines.

Calculator
Presets:

Batch Parameters

Hop Additions

Results

0.0
Total IBU
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Bitterness Category
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BU:GU Ratio
Per-Hop Contribution

How to Use

  1. 1
    Set your batch size

    Enter the batch volume in gallons or liters and the original gravity (OG) of your wort.

  2. 2
    Add hop additions

    For each hop addition, enter the weight, alpha acid percentage, and boil time. Add multiple additions for complex recipes.

  3. 3
    Read the results

    See the total IBU contribution from each hop addition and the overall bitterness level with a BJCP style reference.

About

The International Bitterness Unit (IBU) scale was developed to provide a standardized measurement of beer bitterness. One IBU equals one milligram of iso-alpha acid per liter of beer. During the boil, alpha acids from hops isomerize into iso-alpha acids, which are the primary bittering compounds in beer.

The Tinseth formula, published by Glenn Tinseth in the 1990s, estimates hop utilization as a function of boil time and wort gravity. Higher gravity worts reduce utilization because dissolved sugars inhibit iso-alpha acid extraction. Longer boil times increase utilization up to a plateau around 60-90 minutes.

While IBU provides a useful numerical target, perceived bitterness depends on the balance between hops and malt. A 40 IBU pale ale may taste quite bitter, while a 40 IBU imperial stout may taste smooth due to residual sweetness. The BU:GU ratio (bitterness units to gravity units) is a better indicator of perceived balance.

FAQ

What is IBU?
International Bitterness Units (IBU) measure the concentration of iso-alpha acids in beer. Higher IBU means more perceived bitterness, though malt sweetness and other flavors can offset it.
What formula does this calculator use?
This calculator uses the Tinseth formula, the most widely used method among homebrewers. It accounts for wort gravity and boil time to estimate hop utilization.
What is a good IBU range for my beer style?
It varies widely: light lagers 8-15 IBU, pale ales 30-50 IBU, IPAs 40-70 IBU, and double IPAs 60-100+ IBU. The BJCP style guide defines recommended ranges for each style.
Does hop variety affect IBU?
The alpha acid percentage of the hop variety directly determines bitterness contribution. A high-alpha hop like Columbus (14-16% AA) adds more IBU per gram than a low-alpha aroma hop like Saaz (3-4% AA).
Why do late additions contribute fewer IBUs?
Iso-alpha acid extraction requires sustained boiling. Hops added in the last 5-10 minutes contribute minimal bitterness but maximum aroma and flavor. Dry hops (post-fermentation) add zero IBU.