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Each hop addition contributes IBU based on alpha acids utilized during the boil. Utilization decreases with higher wort gravity and increases with longer boil times.
IBU = (mg alpha acids × Utilization × 1000) / Batch volume (L)Tinseth utilization depends on boil time and wort gravity. Typical 60-minute boil at 1.050 SG: ~30% utilization. Short boils (15 min) and high gravity worts reduce utilization.
Utilization = f(boil time, SG) per Tinseth curveCalculate IBU for each hop addition separately (bittering, flavor, aroma) and sum. Dry hop and whirlpool additions contribute minimal measurable IBU — primarily aroma.
Total IBU = Σ(IBU per addition)Updated: July 2026
5 gal batch, 1.050 OG. 1 oz Cascade 7% AA at 60 min (~28 IBU) + 0.5 oz at 15 min (~10 IBU) + 0.5 oz at flameout (~2 IBU) ≈ 40 IBU total.
1.080 OG reduces utilization. Compensate with more hops: 2 oz Magnum 12% AA at 60 min + 1 oz each at 15 and 5 min targets 80–100 IBU on a 5-gallon batch.
1 oz Saaz 3.5% AA at 60 min in 5 gal, 1.048 OG yields ~18–22 IBU. Hallertau or Tettnang substitute at similar alpha for traditional lager profile.
IBU depends on alpha acid content, not hop weight alone. 1 oz of 12% AA Magnum contributes roughly twice the IBU of 1 oz 6% Cascade at the same boil time.
Dry hops contribute aroma, not significant bitterness. Only count boil and whirlpool additions with meaningful isomerization time in IBU totals.
International Bitterness Units (IBU) quantify hop bitterness in beer. IBU depends on hop alpha acid content, boil time, wort gravity, and batch volume. This calculator uses the Tinseth formula — the standard for homebrew recipe design — to estimate bitterness from each hop addition.