Hop Freshness Calculator

Estimate alpha acid lost during hop storage from age, temperature and packaging — same formula as the Brewfather app.

Alpha acid

Beta acid

Loss after 6 months

Typical alpha loss after 6 months stored loose at 20 °C — from the hop's spec sheet.

Storage duration

Storage temperature

Storage condition

Advanced (optional)

Decay constant k

Override the loss-derived rate constant (per day at 20 °C).

Hop Storage Index

Enter a measured HSI to derive freshness directly — storage settings are then ignored.

Current alpha acid

7.3 %

Want this running live inside your recipes?

Brewfather recalculates your whole recipe as you type — gravity, IBU, color, water and more. Free to start.

How this calculator works

Alpha acids fade as hops age, so older hops bitter less than their label suggests. This tool estimates how much alpha acid remains after storage.

It uses the hop's rated loss after six months, how long and how cold the hops were stored, and how well they were packaged.

The remaining alpha acid is what you should plug into a bitterness calculation for an accurate IBU.

Cold, oxygen-free storage preserves hops dramatically — vacuum-sealed hops in the freezer barely age.
If you have a measured Hop Storage Index from a lab sheet, enter it directly for the most accurate result.