1-2%- this ain't bad..
3-4%- okay, this is getting old..
5-7%- I didn't think this route had a climb..
8-10%- woah, I have no legs today..
11-14%- damn, what a grind, glad I went for the compact
15-18%- why? why? why?..
19% > - what a stupid, stupid sport.. Eff me, I just wanna die...
apres ride- Those climbs were awsome! What a great day!

That's how I calculate them. Backed up by my Garmin of course.