The usual system for rating a trip's difficulty has two components. One rates how strenuous a trip is, and the other rates technical difficulty. The technical rating is based on the Yosemite Decimal System, extended to include skiing.
For physical difficulty
A: easy - up to 5 hours of travel per day
B: moderate - 5 to 8 hours of travel per day
C: hard - 8 to 12 hours of travel per day, heavy loads, etc
D: extreme - more than 12 hours of travel per day, heavy loads, rough terrain, etc.
For technical difficulty
1: on-trail hiking or skiing - good trails
2: off trail hiking, rock scrambling, skiing moderate slopes, straightforward glacier travel. Extremely rugged (north shore) hiking trails may be included here.
3: easy climbing (usually not roped, but pulling on handholds required), skiing steep slopes (up to 30 degrees or so), glacier travel in broken terrain.
4: moderate climbing, usually with a rope. Difficult high mountain skiing.
5: technical rock climbing, extreme skiing
6: aid climbing
Sometimes two technical difficulty grades are used, where a trip has a short difficult section but it mostly at the easier grade. (see Black Tusk Example Below)
Black Tusk B2(3) Wedge Mountain North Arete C3
Trips by Type
Trips by Location
See the guidebooks page.