- Who
- Léon Marchand
- What
- 4:02.50 minute(s):second(s)
- Where
- Japan (Fukuoka)
- When
The fastest swim long course 400 metres medley (male) is 4 minutes 2.50 seconds, achieved by Léon Marchand (France) at the 2023 World Aquatics Championships in Fukuoka, Japan, on 23 July 2023.
Léon Marchand took down the longest-standing long course swimming world record on the books at the 2023 World Championships, finally beating Michael Phelps’ time of 4:03.84 from the 2008 Olympics. Phelps had held the 400 m IM (individual medley) world record since 2002 – set when Marchand was just three months old – the longest time for any swimmer to hold the world record in a single event. The 400 m IM comprises four 100 m legs swim using a different stroke: butterfly, backstroke, breaststroke and freestyle (in that order).
