What is the UTMB Index?

The UTMB Index reflects each runner’s performance level and is calculated across the four UTMB World Series race categories: 20K, 50K, 100K, and 100M.
Runners also receive a General UTMB Index, based on results across all race categories.

A valid UTMB Index is required to enter the lottery for the UTMB Mont-Blanc.

Source: https://utmb.world/en/about