What are Alpha Acid Units?

Alpha Acid Units (AAU) are a simple measure of bittering potential: AAU = Weight (g) x Alpha Acid (%) / 100. This makes it easy to adjust hop amounts when your hops have a different AA% than the recipe specifies.

How do I use AAU in recipes?

If a recipe calls for 1.8 AAU of Cascade, and your Cascade is 6% AA, you need 1.8 / 0.06 = 30g. If next year your Cascade is 7.5% AA, you only need 1.8 / 0.075 = 24g for the same bitterness.

Is AAU the same as HBU?

Yes. Homebrew Bittering Units (HBU) is the same calculation as AAU. Both equal weight multiplied by alpha acid percentage. The terms are interchangeable.

Do alpha acids degrade over time?

Yes, alpha acids degrade during storage. The rate depends on storage conditions — vacuum-sealed hops in a freezer retain potency longest. Always check the crop year and storage method. Use our Hop Freshness Calculator to estimate remaining AA for older hops.

What is a typical alpha acid range?

Bittering hops: 10-17% AA (e.g. Magnum 12-14%, Columbus 14-16%). Dual-purpose: 5-10% (e.g. Cascade 5-7%, Centennial 9-11%). Aroma hops: 2-6% (e.g. Saaz 3-4%, East Kent Goldings 4-6%). Higher AA hops need less weight for the same bitterness.

BrewCalcs

Alpha Acid Calculator — AAU Calculator

Calculate alpha acid units and adjust hop weights for different AA percentages.

Hop Weight

Weight of hops to add

Alpha Acid

Alpha acid percentage of your hops

Target AAU (optional)

Enter a target to find the weight needed

How We Calculate This

AAU Calculation

AAU = Hop Weight (g) x Alpha Acid (%) / 100

To find weight for a target AAU: Weight = Target AAU / (Alpha Acid / 100)

Frequently Asked Questions

Related Calculators

IBU Calculator

Calculate International Bitterness Units using Tinseth or Rager formulas.

Hop Utilisation Calculator

Calculate IBU contribution, utilisation percentage and bittering versus flavour ratio from alpha acid, hop weight, boil time and wort gravity.

Hop Substitution Calculator

Find equivalent hop amounts when substituting varieties.

Dry Hop Calculator

Calculate dry hop amounts based on desired intensity and batch size.

First Wort Hop Calculator

Calculate IBU contribution from first wort hopping additions.

Last updated: 2025-02-20

All calculations are estimates. Always verify values and adjust based on your equipment and ingredients.