A half marathon is 21.0975 kilometers, or about 13.1 miles (13 miles 192.5 yards), exactly half the distance of a full marathon. It is often called a 21K or 21.1K, and races are frequently held alongside a full marathon on a shortened version of the same course. World Athletics recognizes official records at the distance; the men’s record is 56:51, set by Yomif Kejelcha in Buenos Aires in 2026.
Source: Wikipedia, Half marathon