Hop IBU estimation in whirlpool

[Mike Newman]

This Saturday is my HBC big brew day and I reached out to Boulevard Brewing Company for their Tank 7 recipe (which they gave me) so that I may brew it. The recipe gives the hop estimations in IBU at flameout as 6.3 IBU (cascade) and 8.3 IBU (Amarillo). Can anyone help me with what this would calculate to for a 5 gallon batch? I have read the BYO article on hop whirlpool and how to calculate estimates from AA % but I am still unsure if my math is anywhere near right!

 

[dmtaylor]

Whirlpool is approximately the same as if boiled for half the time. For example, a 20-minute whirlpool gives about the same IBUs as if those hops had been boiled for 10 minutes. It's not exact, but pretty close.