With the London Marathon being run today, it is timely to remember the metric origins of the marathon, and to puncture the myth that it is a race measured in imperial units.
No lesser an authority than the New York Times ran a story this weekend which opened with the sentence “At the Summer Olympics, the marathon will be the only foot race measured by the standard system instead of the metric system,” and describes the course length as “the precise distance of 26 miles 385 yards.” Sadly for the newspaper, the marathon course will be neither measured by the “standard” (or to British ears imperial) system, nor will it be precisely 26 miles and 385 yards. The rules of the marathon are quite clear; it is a race of 42,195 metres, and must show kilometre marker posts for runners for any race times to stand as official times. More precisely, race officials must allow one metre per kilometre to take account of any measuring inaccuracies, as the races are normally run on streets rather than tracks, and so the racing line could be slightly inaccurate. There are mentions of neither miles nor yards in the race rules. So how long is 42,195 metres? In the imperial system, it would be 26 miles, 385 yards and 0.4752 inches. So if any organiser were to measure a race using the imperial system, and measure precisely 26 miles 385 yards as advocated by the New York Times, it would fall short of 42,195 metres, and would not be a marathon.