Hop Utilization (Tinseth)

About this calculator

The Tinseth formula, developed by Glenn Tinseth and the most widely used hop-utilization model among homebrewers, estimates what fraction of a hop addition’s alpha acids actually isomerize into bittering compounds during the boil. It multiplies two factors: a “bigness factor” that falls as boil gravity rises (higher-gravity worts extract bitterness less efficiently), and a “boil time factor” that climbs toward a ceiling the longer the hops boil, since utilization increases with time but with diminishing returns.

Homebrewers use the resulting utilization percentage to calculate IBUs (International Bitterness Units) contributed by each hop addition — combining alpha-acid percentage, hop weight, batch volume, boil gravity and boil time — which is essential for hitting a recipe’s target bitterness, since the same hop amount added at 60 minutes contributes far more bitterness than the same amount added at 10 minutes.

This calculator takes your boil gravity and boil time and returns the Tinseth utilization percentage for that addition.