World record progression 400 metres men

The first world record in the 400 m for men (athletics) was recognized by the International Amateur Athletics Federation, now known as the International Association of Athletics Federations, in 1912. The IAAF ratified Charles Reidpath's 48.2 performance set at that year's Stockholm Olympics as a world record, but it also recognized the superior mark over 440 yards (402.34 metres) run by Maxie Long in 1900 as a world record.

To June 21, 2009, the IAAF has ratified 23 world records in the event.

The following tables show the world record progression in the men's 400 metres, as ratified by the IAAF.

(+) plus sign denotes en route time during longer race
"y" denotes time for 440 yards, ratified as a record for this event
"A" indicates that the time was set at altitude.

From 1975, the IAAF accepted separate automatically electronically timed records for events up to 400 metres. Starting January 1, 1977, the IAAF required fully automatic timing to the hundredth of a second for these events.

Lee Evans' 1968 Olympic gold medal victory time of 43.86 was the fastest recorded result to that time.

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