Converting DND 3.5 DC to DFRPG

[dripton]

Maybe this is overly simplistic, but I treat a DC 15 task as skill +0, and add +2/-2 to skill for each 5 points above or below that. Easy enough to remember:

DC 5: +4
DC 10: +2
DC 15: 0
DC 20: -2
DC 25: -4
DC 30: -6
DC 35: -8
DC 40: -10

Then I'll add or subtract another +1 for the numbers which are more than 1 DC off from a multiple of 5. So DC 19 and 21 are -2 just like DC 20, but DC 17 and 18 are just -1, and DC 22 and 23 are -3.

Note: I haven't played much D&D 3.5, so I can't say if these are exactly right, but the module I converted seems to have a lot of DCs in the 15 to 25 range, and this yields modifiers in the 0 to -4 range, which seems like a reasonable challenge for Dungeon Fantasy characters, who tend to have pretty good ability and skill levels. And it has occasional DCs in the 40 range for tasks that are supposed to be very hard, and a -10 does reflect very hard (but not impossible with high skill) pretty well. So I've been pretty happy with this simple system.