Why a Marathon Is 42.195 km

Feed the Reader

4 hours ago

4 min read

At the end of every marathon, the finish clock sits above a line drawn at a strangely precise distance from the start: 42.195 kilometres, or 26 miles 385 yards.

Most races come in round numbers. Five kilometres, ten kilometres, a hundred metres. The marathon's distance has three decimal places. Something very specific must have happened to produce a number like that. It did.

The name is ancient. The number isn't.

The marathon takes its name from a Greek legend. After the Battle of Marathon in 490 BCE, the story goes, a messenger ran all the way to Athens with news of the victory. When the modern Olympic Games began in Athens in 1896, the organisers included a long road race inspired by that tale.

But the legend didn't come with a tape measure. Early Olympic marathons were run over roughly 40 kilometres, and for years the distance kept changing from one Games to the next.

A route between a castle and a stadium

In 1908, the Olympics came to London. It was agreed in advance that the marathon would be about 25 miles, or 40 kilometres. Then the organisers planned the route.

They chose to start the race at Windsor Castle, west of London, and finish inside the new Olympic stadium at White City. With the King's permission, the start was set on a lawn within the castle grounds, partly to keep crowds from getting in the way, and members of the royal family came to watch the runners set off.

At the other end, the plan was for the race to finish on the stadium track, at the finishing line directly in front of the Royal Box.

The distance from Windsor to the stadium came to about 26 miles. The route was fixed by places, not by a target number: a castle at one end, a royal viewing box at the other.

Where the 385 yards came from

The awkward tail of the distance comes from the stadium itself.

The first plan was for runners to enter the stadium and run a full lap of the track before finishing. Shortly before the Games, that had to change. The entrance originally intended for the marathon turned out to be unsuitable, so the runners were brought in through a different entrance, diagonally opposite the Royal Box, and the direction they ran around the track was switched so that more spectators would get a good view of the finish.

The finishing line itself stayed put, in front of the Royal Box. Measured from the new entrance, the distance round the track to that line was 385 yards.

So the official distance became about 26 miles to the stadium, plus 385 yards on the track. Converted to metric, that's 42.195 kilometres.

It didn't stick straight away

Here's the surprising part. The 1908 distance didn't immediately become the rule.

Later Olympic marathons were still run over different lengths. The 1912 race in Stockholm was about 40.2 kilometres, and the 1920 race in Antwerp, at 42.75 kilometres, was probably the longest Olympic marathon of all. It was only in 1921 that athletics' international governing body, then called the International Amateur Athletic Federation, officially fixed the marathon at 42.195 kilometres. The 1924 Paris Olympics were the first Games to use it as the set distance.

The federation's records reportedly don't explain why it chose that particular figure. But by 1921, the London distance had already been adopted by many races around the world.

The race that made the number famous

One reason it caught on may be that the 1908 race was unforgettable.

Italy's Dorando Pietri was the first runner to reach the stadium, but he was in a desperate state from exhaustion and dehydration. On entering the track he went the wrong way, and when officials redirected him, he collapsed. They helped him up. He fell several more times over those final few hundred metres, and each time officials helped him to his feet. Eventually he staggered across the line in first place, in front of a packed stadium.

The American team protested that he'd been helped, and Pietri was disqualified. Johnny Hayes of the United States, who had finished second, was awarded the gold medal. The next day, Queen Alexandra presented Pietri with a special cup in recognition of his effort.

The drama made headlines around the world and set off a craze for marathon running. Pietri and Hayes later raced each other again as professionals, over the same 26 miles 385 yards, and many other marathons adopted the London distance.

Tidy stories, untidy history

You'll often read neater versions: that the distance was stretched so royal children could watch from a nursery window, or because the Queen insisted. The details vary from telling to telling, and they're hard to pin down. What the record supports is simpler. The start was at Windsor Castle, the finish was in front of the Royal Box, and the 385 yards came from how the runners entered the stadium and where the line was. The royal box is the anchor. Royal children did watch the start, beneath the castle's nursery windows, but there's no good evidence the distance was stretched for their sake.

Back to the finish line

So the next time you see a marathon finish clock, or a medal engraved with 42.195, you're looking at a souvenir of one summer's day in London in 1908: a route from a castle lawn to a stadium, and a stretch of track that happened to measure 385 yards.

Wherever a marathon is run today, every runner is covering the distance of that one London course.