Yosemite Decimal System
(Route Rating Systems)

In the 1920s, Willo Walzenbach defined a rating system to compare and describe routes in the Alps. This is the basis of today's UIAA rating system. In 1937 a modified version of the Walzenbach system was adopted by the Sierra Club and then altered in the 1950s to more accurately describe the technical climbing being done at Tahquitz and Suicide Rock in California. It was altered by adding a 10 point decimal system to class 5 climbing, (5.0 - 5.9), which has become known as the Yosemite Decimal System (YDS). At the time it was developed, it was believed that 5.9 was the limit of a persons climbing ability, but in the 1970s, rising standards led to the need for an open-ended scale. The strict decimal system was abandoned and 5.10 through 5.14 was adopted.1

How Rock Is Rated

The YDS rates a pitch according to the most difficult move on it. A route may be divided into several pitches of varying degrees of difficulty.

Class 1:
Walking and hiking, generally, hands are not needed.
Class 2:
Hiking, mostly on established trails involving some scrambling with occasional use of hands.
Class 3:
Climbing or scrambling with moderate exposure. Angle steep enough that hands are needed for balance.
Class 4:
Intermediate climbing with exposure extreme enough that most mountaineers will want a belay. A fall could be serious or fatal. Intermediate climbing requires the use of your hands and arms for pulling yourself up.
Class 5:
Technical rock climbing is encompassed in Class 5 climbing. A rope, specialized equipment and training are used by the leader to protect against a fall.
A person of reasonable fitness can climb at this level with little or no rock climbing skills.
Requires rock climbing skills or strength.
Good rock climbing skills, rock shoes, and strength are generally needed to climb at this level.
Excellent rock climbing skills and training are required to climb and maintain the ability to climb this level of rock.
Many climbs have also been subcategorized with a (+) or a (-) indicating more or less difficult. I have found that some guide books will often use the (+) (-) ratings for climbs easier than 5.10. Many guide books use a,b,c,d to define the difficulty of a climb rather than the (+) or (-). For example, a 5.12d would be more difficult than a 5.12b.
Class 6:
Rock so shear and smooth that it is unclimbable without the use of aid.

Since the standard usage of the Yosemite Decimal System defines only the hardest move on a pitch, or the hardest pitch on a multipitch route, a seriousness factor was introduced to give an indication of the relative danger of the climb. This system was developed in 1980 by James Erickson.

Protection is adequate; if properly placed a fall would not be too serious.
Protection is considered inadequate; there is a potential for a long fall, and a falling leader would take a hard wipper, possibly suffering injuries.
Inadequate or no protection; a fall would be very serious and perhaps fatal.


Grades are used for alpine climbing to tell the climber how much time it should take to complete the climb by an experienced climber.2 Grades are defined using the following factors. The length of the climb, the number of hard pitches, the difficulty of the hardest pitch, commitment, possible routefinding problems, ascent time required, rock or icefall hazards, and the remoteness of the climb.3

Grade Description

  1. Normally only requires one to three hours for the technical portion.
  2. Generally between three and six hours to complete the technical portion.
  3. A good full day on the climb.
  4. Expect to take a long full day of technical climbing. The hardest pitch is usually no less than 5.7.
  5. One to two days. You should expect to spend the night on the wall. The hardest pitch is rarely less than 5.8.
  6. Two or more days on the wall are usually required for the technical portion. The climb will involve considerably difficult free climbing and/or aid climbing.

Ice Climbing

Ice Classification
(AI, WI, or M)
Rock Classification
1 Up to 50° snow or 35° ice 1st to 3rd Class
2 Up to 60° snow or 40° ice 4th Class
3 Up to 80° snow or 75° ice 5.0 - 5.7
4 Up to vertical snow or 85° ice 5.8 - 5.9
5 Overhanging cornices or 90° ice 5.10
6 Very thin or technical 90° ice 5.11
7 95° or overhanging mixed 5.12
8 Technical overhanging mixed 5.13


  1. Freedom Of The Hills, 6th Edition
  2. Rock Jocks, Wall Rats, and Hang Dogs
  3. Freedom of the Hills, 5th Edition