Why Is a Marathon 26.2 Miles? A Legend, a Royal Box and a Committee
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Every marathon in the world is 42.195 kilometres, or 26 miles and 385 yards, a distance too specific to be a round number in any system. It is not an ancient measurement and it was not chosen for any athletic reason. It is the length of one particular course laid out in London in 1908, which became the rule thirteen years later because it happened to be the course of the race everyone remembered.
The legend of Pheidippides
The name goes back to the Battle of Marathon in 490 BCE, when an Athenian army defeated a Persian invasion force on the plain of Marathon about 40 kilometres from Athens. The story that a runner carried news of the victory to Athens, announced it and dropped dead is first told by the writer Plutarch some six centuries later, and Lucian later gave the runner the name Philippides. The historian Herodotus, writing much closer to the events, has a runner named Pheidippides covering the far greater distance from Athens to Sparta and back to ask for help before the battle, about 240 kilometres each way, and surviving.
The dying messenger is almost certainly a legend, but it was the legend that Michel Breal, a French scholar, had in mind when he suggested a long race from Marathon to Athens for the first modern Olympic Games in 1896. That race was about 40 kilometres and was won by a Greek water-carrier, Spyridon Louis, which sealed the event's popularity in its home country.
Forty kilometres, more or less
For the next decade the marathon had no fixed length. The 1896 race was around 40 kilometres, the 1900 Paris race about 40.26, the 1904 St Louis race just under 40, and the early Boston Marathon, first run in 1897, was about 39.4 kilometres. Organisers picked a start and finish that suited the city and measured what they got. Nobody thought the exact figure mattered, because no two courses were comparable anyway.
London, 1908
The London Olympics of 1908 planned a marathon of about 26 miles from Windsor Castle to the new stadium at Shepherd's Bush. The story most often told is that the start was moved onto the castle's east lawn so that the royal children could watch from the nursery windows, and the finish was placed in front of the royal box in the stadium, which together produced 26 miles and 385 yards. The details are disputed and the route was adjusted several times for practical reasons, but the final measured distance is not in doubt.
The race itself became famous for its ending. The Italian runner Dorando Pietri entered the stadium first, collapsed several times on the track, was helped across the line by officials and was disqualified, with the gold medal going to the American Johnny Hayes. Queen Alexandra gave Pietri a special cup the next day, the newspapers made him a hero, and the marathon was suddenly the most talked-about event in athletics.
How the odd number became the rule
The 1912 and 1920 Olympic marathons were run over 40.2 and 42.75 kilometres, so London's figure was not yet a standard. What fixed it was the professional racing craze that followed Pietri's collapse. He and Hayes turned professional and raced each other repeatedly in the United States, and promoters advertised the events as being over the London distance, which was the one the public knew. By the time the International Amateur Athletic Federation met in 1921 to set a standard, 42.195 kilometres had become the marathon in the public mind, and the committee adopted it. It has been the distance ever since, including at every Olympics from 1924. The steps that produced it:
- •1896: a 40-kilometre race from Marathon to Athens, inspired by legend
- •1897 to 1907: courses of roughly 40 kilometres, none the same
- •1908: the London course from Windsor to the stadium measures 26 miles 385 yards
- •1908 to 1920: the Pietri drama makes the London distance the famous one
- •1921: the IAAF adopts 42.195 kilometres as the standard
What the distance does to a runner
The number is arbitrary, but it happens to sit just beyond the point where the body's stored carbohydrate runs out. A trained runner carries roughly 2,000 calories of glycogen in muscle and liver, enough for about 30 kilometres at racing pace, after which the body must burn fat, which it cannot do as quickly. The result is the wall, the sudden heaviness runners describe at around 20 miles, and much of marathon training and fuelling is about pushing it beyond the finish line.
Had the London organisers laid out 24 miles, the event would be a different sport, hard but without its signature collapse. The royal nursery, if the story is true, gave the marathon its cruelty as well as its distance.
How a course is actually measured
Once the distance was fixed, the practical problem became making sure every course really is 42.195 kilometres. Certified road courses are measured with a bicycle fitted with a precision counter on its front wheel, first calibrated by riding it several times along a straight section of road whose length has been measured with a steel tape. The measurer then rides the course along the shortest route a runner could legally take, cutting every corner as tightly as allowed. To make sure no course is ever short, an extra tenth of a percent is added, about 42 metres, so every certified marathon is very slightly long.
A course can be accurately measured and still not count for world records. The rules require that the start and finish not be too far apart in a straight line, so a tailwind cannot carry runners the whole way, and that the course not drop more than an average of one metre per kilometre overall. The Boston Marathon, which runs point to point and loses well over a hundred metres of height from start to finish, fails both tests, which is why fast times there are not ratified as records. Running an ordinary course, you are covering a distance defined to the metre.
What the distance means as a pace
The odd length makes pace arithmetic awkward, so runners learn a few benchmarks. To finish in four hours you need to average about 5 minutes 41 seconds per kilometre, or 9 minutes 9 seconds per mile, for the whole distance. A three-hour marathon needs about 4 minutes 16 seconds per kilometre, or 6 minutes 52 seconds per mile. Because the body's fuel is limited, starting even slightly faster than goal pace uses up glycogen sooner, and seconds banked early are often lost, and more, in the closing miles, which is why coaches advise settling into an even pace from the first kilometre.
At the top of the sport the numbers are startling. The men's world record of 2 hours and 35 seconds, set by Kelvin Kiptum of Kenya in Chicago in 2023, works out at about 2 minutes 51 seconds per kilometre, close to 21 kilometres an hour, which is like running each 100 metres in about 17 seconds for two hours. Eliud Kipchoge covered the distance in under two hours in Vienna in 2019, but that time is not recognised as a record, because the run was specially staged, with relays of pacemakers rotating in and out and drinks handed to him from a bicycle.
The takeaway
A marathon is 42.195 kilometres because that was the length of the 1908 London Olympic course, which became famous through Dorando Pietri's collapse and was adopted as the standard in 1921. The distance owes nothing to ancient Greece beyond its name and its legend, and by chance it runs a few miles past the point where the body's fuel gives out.