Most 5.15 routes climbed

The person with the most ascents of unique routes in the 5.15 range (5.15a-5.15d) is Adam Ondra (Czech Republic). As of 3 February 2022, Ondra had climbed 70 routes in the 5.15 range.

Technical rock climbs in the US and many parts of the world are graded using the Yosemite Decimal System to convey the overall difficulty. The scale starts at 5.0 and continues all the way up to the current hardest grade, 5.15d. The increments in between are 5.1, 5.2, 5.3, 5.4, etc., all the way up to 5.9. At 5.10, the decimal grades are subdivided further using letters from a to d, so: 5.10a, 5.10b, 5.10c, 5.10d, 5.11a, 5.11b, 5.11c, 5.11d, 5.12a, 5.12b, etc. The additional difficulty between any two grades on the scale (5.9 to 5.10; or 5.13c to 513d) is meant to be relative to the difficulty of the prior grade.

Grades are established based on a rough consensus system. The first ascensionist usually suggests a grade. Repeat ascensionists than either confirm it, or suggest alternative grades. Climbs in the 5.15 range are the pinnacle of the sport, attempted only by elite full-time climbers.