🌿 IBU Calculator
Add each hop's weight, alpha acid, and boil time, then enter your batch volume and wort gravity to see the total bitterness in IBU — calculated with the industry-standard Tinseth method.
🌿 Estimate Your Bitterness
What is an IBU Calculator?
It predicts how bitter your beer will taste before you ever brew it. Enter your hop schedule — the weight, alpha-acid percentage, and boil time of each addition — plus your batch volume and wort gravity, and it estimates the total International Bitterness Units using Glenn Tinseth's utilization model.
Use it to dial in a recipe to a target style, to balance bitterness against maltiness, or to substitute one hop for another while holding the IBU steady. Because utilization depends on gravity and time, the tool weighs every addition individually so late and dry additions count for less than a long bittering charge.
❓ Frequently Asked Questions
How does the IBU calculator work?
For each hop addition it applies the Tinseth model: a 'bigness factor' from your wort gravity and a boil-time factor combine into a utilization percentage, which is multiplied by the concentration of alpha acids (from the hop's weight, alpha-acid percentage, and your batch volume). Adding up every hop's contribution gives the total International Bitterness Units.
What is the Tinseth formula?
Developed by Glenn Tinseth, it's the most widely used homebrew model for estimating hop bitterness. It captures two key effects: higher-gravity worts extract fewer bitter compounds (the bigness factor), and utilization rises with boil time but plateaus after about an hour (the boil-time factor). It's an estimate of isomerized alpha acids, not a lab measurement.
What's a typical IBU range for beer styles?
Light lagers and wheat beers often sit around 8–18 IBU, pale ales 30–45, and IPAs 40–70 or higher, while a big double IPA can exceed 100. Bitterness is best judged alongside gravity — the same IBU tastes sharper in a light beer than in a malty one, which is why brewers also look at the bitterness-to-gravity ratio.
Why does wort gravity change the bitterness?
Alpha acids isomerize (become bitter and soluble) less efficiently in a thicker, sugar-rich wort. Tinseth's bigness factor lowers utilization as gravity rises, so the same hops in a strong wort yield fewer IBU than in a thin one. That's why the calculator asks for your boil (wort) gravity, not just the batch volume.