UIAA scale

In rock climbing, mountaineering and other climbing disciplines, climbers give a grade to a climbing route that concisely describes the difficulty and danger of climbing the route. Different aspects of climbing each have their own grading system, and many different nationalities developed their own, distinctive grading systems.

There are a number of factors that contribute to the difficulty of a climb including the technical difficulty of the moves, the strength and stamina required, the level of commitment, and the difficulty of protecting the climber. Different grading systems consider these factors in different ways, so no two grading systems have an exact one-to-one correspondence.

Climbing grades are inherently subjective. They may be the opinion of one or a few climbers, often the first ascentionist or the author(s) of a guidebook. A grade for an individual route may also be a consensus reached by many climbers who have climbed the route. While grades are usually applied fairly consistently across a climbing area, there are often perceived differences between grading at different climbing areas. Because of these variables, a given climber might find a route to be either easier or more difficult than expected for the grade applied.

In 1894, the Austrian mountaineer Fritz Benesch introduced the first known grading system for rock climbing. The Benesch scale had seven levels of difficulty, with level VII the easiest and level I the most difficult. Soon more difficult climbs were made, which originally were graded level 0 and 00. In 1923, the German mountaineer Willo Welzenbach compressed the scale and turned the order around, so that level 00 became level IV-V. This "Welzenbach scale" was adopted in 1935 by French mountaineers like Lucien Devies, Pierre Allain and Armand Charlet for routes in the Western Alps and finally in 1947 in Chamonix by the Union Internationale des Associations d'Alpinisme. It prevailed internationally and was renamed in 1968 as the UIAA scale. Originally a 6-grade scale, it has been officially open-ended since 1979.

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