Enter your batch size, original gravity, and up to three hop additions (weight, alpha acid %, and boil time) to calculate your beer's IBU (International Bitterness Units) using the Tinseth formula. You'll get the total IBU for your recipe plus a per-addition breakdown — perfect for dialing in bitterness on any homebrew style.
Total IBU
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Hop 1 IBU
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Hop 2 IBU
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Hop 3 IBU
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Bitterness Level
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IBU stands for International Bitterness Units, a scale that measures the bitterness of beer contributed by alpha acids in hops. The scale runs from 0 (no bitterness, like fruit beers) up to 120+ (extremely bitter beers like Imperial IPAs). Knowing your target IBU helps you craft a beer that fits its intended style and balances sweetness from malt against hop bitterness.
The Tinseth formula, developed by Glenn Tinseth, calculates IBUs by factoring in hop weight, alpha acid percentage, boil time, and wort gravity. The utilization factor (U) is calculated as: U = 1.65 × 0.000125^(SG-1) × (1 − e^(−0.04 × time)) / 4.15. It is widely regarded as one of the most accurate IBU estimation methods for homebrewers.
Different styles have very different bitterness targets. Light lagers typically fall between 8–12 IBU, wheat beers 10–20, pilsners 25–45, pale ales 30–50, IPAs 40–70, and Imperial IPAs or barleywines can reach 80–120 IBU. Matching your IBU to your style ensures the bitterness is appropriate and well-balanced.
Longer boil times extract more alpha acids from hops, significantly increasing utilization and therefore IBU contribution. A 60-minute addition will contribute far more bitterness than a 15-minute or flameout addition of the same weight. Late hop additions (under 10 minutes) contribute minimal IBUs but add significant aroma and flavor.
Higher wort gravity reduces hop utilization — the sugars in the wort inhibit alpha acid isomerization. This means that if you're brewing a big, high-gravity beer, your hops will be less efficient and you'll need more to hit the same IBU target compared to a lower-gravity recipe.
When using US units, enter batch size in gallons and hop weight in ounces. When using metric units, enter batch size in liters and hop weight in grams. The calculator automatically adjusts the formula constants to produce accurate IBU results regardless of which unit system you choose.
This calculator supports up to three hop additions, which covers the most common homebrewing scenarios (bittering, flavor, and aroma additions). For more complex recipes with additional dry hop or whirlpool additions, you can run the calculator multiple times and add the results, keeping in mind that dry-hopping contributes negligible IBUs.
IBU calculators provide estimates based on idealized conditions. Real-world factors like hop freshness (alpha acid degradation), yeast strain, fermentation conditions, hop form (pellet vs. whole leaf), brewing water chemistry, and actual boil vigor can all shift the perceived and measured bitterness. Use this tool as a reliable guide, not an exact guarantee.