I calculated the IBU to be somewhere around 23-25.
Willamette is around 4.8%
Mt. Hood is 5.8%
I used .5 oz of each.
So, my math is:
.5oz of mt. hood @ 5.8% = 2.9 AAU
.5oz of willamette @ 4.8% = 2.4 AAU
IBU = AAU x U (used respective number via John Palmer's table) x 75 / Volume of recipe
2.9 x .256 (boil gravity was 1.045 and mt. hood was a 60 minute addition) x 75 / 3 (3 gallon batch) = 18.56
2.4 x .129 (15 min. addition for willamette) x 75 / 3 = 7.74
18.56+7.74=26.3
I would figure from an IBU of that range, it would have a comparable bitterness to almost a Sam Adams kind of kick.
Name:Mt. Hood
Grown:US
Profile:
Mild, clean aroma. One of three hops bred as domestic replacements for Hallertauer Mittelfrüh.
Usage: Finishing for German style lagers
Example: Anderson Valley High Rollers Wheat Beer
AA Range:3.5 - 8%
Substitute:
Hallertauer Mittelfrüh, Hallertauer Hersbrucker, Liberty,
Tettnang, Ultra
Name:Willamette
Grown:US
Profile:
Mild, spicy, grassy, floral aroma
Usage:Finishing / dry hopping for American / British style ales
Example:
Sierra Nevada Porter, Ballard Bitter, Anderson Valley Boont Amber, Redhook ESB
AA Range:4 - 7%
Substitute:Fuggles
This hop info is straight from John Palmer's book. I know the hops I ended up using are more of a finishing hop, but I kinda expected a little more bitterness than what I have.
edit:
My issue isn't so much wanting to "buck the system" and make a hoppy amber (which is supposedly not intended to be so, but that is a discussion for another time), as it is having results match predictions. My math says one thing, but my tongue says another. Albeit, I am not exactly a seasoned veteran of determining approximate IBU from taste. I'm just going from the info that says the hops used, in the amounts stated, will produce a bitterness similar to X beer.