Ask Mr. Wizard

Measuring IBUs: Part science, practice, and opinion


Chris Patterson — Downers Grove, Illinois asks,

In the March April 2020 issue, the Replicator’s review of Knotted Root Brewing Company’s Perpetually Unimpressed clone states that hops added after flameout are not included in the IBU calculation, yet this beer is rated at 80 IBUs. With the advent of hazy IPAs how are the after-boil hop additions being accounted for in the IBU calculation?

My view about how international bittering units or IBUs are used by the modern brewer is a blend of science, practice, and opinion. The science behind the IBU is something I have
Response by Ashton Lewis.