Yosemite Decimal System at a glance
- Class 1
- Trail walking
- Class 2
- Rough ground, occasional hands
- Class 3
- Scrambling, a fall injures
- Class 5
- Roped technical climbing
What the classes mean on the ground
Class 1 is walking on a trail. Class 2 is rough off-trail ground where you might put a hand down, which covers most talus and scree. Class 3 is real scrambling: you are using your hands to make upward progress, and a fall would hurt you seriously. Class 4 is scrambling with enough exposure that many parties rope up. Class 5 is technical climbing, subdivided from 5.0 upward, and is a different sport.
The line worth knowing is between 2 and 3, because that is where consequence changes. On class 2 a slip is a scrape. On class 3 a slip is a fall, and a fall is an injury or worse. Trip reports that describe a route as a hike right up to a short class 3 step are describing something a lot of people should turn around at.
Why the ratings feel inconsistent
They are subjective and they are regional. A route rated class 3 in the Sierra is often harder than a class 3 in the Rockies, and guidebook authors sandbag routes they know well. The rating also assumes dry rock in good conditions: any class 3 becomes something else entirely when wet, iced or snow-covered.
It also says nothing about exposure or route length. A short class 3 move a meter above a ledge and a hundred meters of class 3 above a drop carry the same number and completely different consequences.
What this means when you're choosing
- Whether a route's rating is for dry conditions, which almost all of them are
- Sticky rubber and a stiff enough edge, which is what class 3 rock asks of a shoe
- How long the hard section is, since the class says nothing about its length
The common mistake
Reading class 3 as a slightly harder hike
Class 3 is where a fall stops being a scrape and becomes an injury. A trip report calling a peak an easy hike with a bit of class 3 near the top is describing terrain where a meaningful number of parties should turn around, particularly if the rock is wet.
Common questions
What is the difference between class 2 and class 3?
Consequence. On class 2 you might put a hand down and a slip is a scrape. On class 3 you are using your hands to climb and a slip is a fall that injures you. That is the line most hikers should decide about in advance.
Do I need a rope for class 4?
Many parties use one. Class 4 is scrambling with enough exposure that a fall is likely to be fatal, so whether you rope up is a judgement about your own comfort on that specific rock rather than a rule.
Are the ratings consistent between areas?
No. They are subjective and regional, and Sierra ratings in particular have a reputation for being stiff. All of them assume dry rock in good conditions.
Where this is defined
- Climbing and scrambling grades, American Alpine Club
- Wilderness climbing and scrambling information, National Park Service