To June 21, 2009, the IAAF has ratified 27 world records in the event.
[1] (y) indicates time for 440 yards (402.34 metres), ratified as a record for this event (+) plus sign denotes en route time during longer race The "Time" column indicates the ratified mark; the "Auto" column indicates a fully automatic time that was also recorded in the event when hand-timed marks were used for official records, or which was the basis for the official mark, rounded to the 10th of a second, depending on the rules then in place.
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.
[1] Riitta Salin's 50.14 from 1974 was the fastest recorded result to that time.