| Scale | WI1 to WI7+ |
| Rates | Steepness, ice quality, protection |
| Related scales | AI (alpine ice), M (mixed) |
| Difficulty | Advanced concept |
Ice climbing grades use the WI (water ice) scale, running from WI1 to WI7+, to rate the difficulty of frozen waterfalls and ice routes. The number reflects steepness, ice quality, and how sustained and protectable the climbing is. A parallel ‘AI’ (alpine ice) scale is used for glacier and alpine ice that is generally less steep.
How it works
WI1 is low-angle; WI4–5 are steep, sustained pillars; WI7+ is overhanging and fragile. The grade bundles steepness, continuity, ice quality, and protection.
WI vs M vs AI
Pure ice gets a WI grade; mixed routes get an ‘M’ grade; alpine ice uses ‘AI’. See ice climbing.
Convert it
Compare difficulty across systems with the grade conversion guide.
Frequently asked questions
How does the WI ice scale work?
WI grades run from WI1 (low-angle ice) up through WI4 and WI5 (steep, sustained pillars) to WI7 and beyond (overhanging, fragile, poorly protected ice). The number bundles steepness, how continuous the hard climbing is, ice quality, and how hard it is to place protection.
What's the difference between WI and M grades?
WI grades pure water ice; M grades rate mixed climbing, where ice tools and crampons are also used on bare rock. A route that combines steep ice with rock sections will carry an M grade, while a frozen waterfall gets a WI grade.
What is the AI grade?
AI stands for alpine ice, used for the firmer, generally lower-angle ice found on glaciers and alpine faces. It uses similar numbers to WI but signals a different, mountaineering-oriented context rather than steep waterfall ice.
Sources
- Ice grading — American Alpine Club