Hops Alpha Adjustment
Your recipe calls for hops at one alpha acid % — but the hops you've got are different. This calculator finds the right weight to use so your bittering stays on target.
How to use it
- Check the alpha acid % and weight your recipe calls for.
- Check the alpha acid % on the packet of the hops you actually have.
- Enter all three figures — the calculator gives you the adjusted weight to use.
Why does alpha acid % vary?
Alpha acid content changes year to year with growing conditions, and even batch to batch from the same farm. Always check the % printed on your pack rather than assuming a fixed figure for a variety — this is exactly what this calculator is for.
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Matching a recipe's bitterness with different hops
What it does: recipes are written for hops of a certain alpha acid percentage. Your hops will often be different, because alpha acid changes from harvest to harvest. This calculator tells you how much of your hops to use to get the same bitterness.
How to use it: enter the alpha acid percentage the recipe assumes, the weight the recipe asks for, and the alpha acid percentage printed on your pack.
The formula in plain words: multiply the recipe's alpha acid by the recipe's weight, then divide by your hops' alpha acid. The bittering "units" stay the same, just from a different weight of hops.
Worked example: a recipe asks for 30g of a 5.5% hop, and your pack says 7.2%. 5.5 × 30 ÷ 7.2 = 22.9g, so use about 23g.
This matters most for the bittering addition at the start of the boil. For late and dry-hop additions, which add aroma rather than bitterness, most brewers just use the weight in the recipe. If you're swapping to a different variety altogether, try the hop substitution tool.