How long is a marathon? How far is it in miles?

If a non-runner with a rudimentary knowledge of sports were to be asked how long a marathon is, the answer might be “26 miles” or “42 kilometers”, depending on where they were in the world and which unit of distance they used. This is a perfectly acceptable answer and more mathematically accurate than another common answer, which is “too long.”

The distance for an official marathon, which avid runners might point out, is actually 26.2 miles, or to be absolutely exact, 26 miles and 385 yards. That’s 42.195 kilometers for metric-system users.

The International Amateur Athletic Federation (IAAF) set this standard distance in May 1921, after years of having it bumping around between 24 to 26 miles.

Related Olympic stories: What is the longest race in the Olympics?

What accounts for this particular distance? Why the need for decimal points and such specificity?

Apparently, the English royal family is to be credited with this (or blamed for it if one is a runner suffering through those last 385 yards).

The initial distance of a marathon

When the marathon made its debut in the first modern Olympic Games in 1896 in Athens, runners followed the legendary ancient route of a messenger who is said to have run from Marathon to Athens to report that the Greeks had defeated an invading army of Persians. This course had a distance of approximately 25 miles.

After those first games, marathons hovered around the 25-mile mark, and no strict standard was set.

The role of the royal family

Then came the 1908 London Olympics. Just like in previous races, the marathon was supposed to run a distance in the ballpark of 25 miles.

But as the story goes, the royal family requested that the race start directly in front of Windsor Castle and finish right before the royal family’s viewing box at the Olympic stadium.

This route happened to have a distance of 26 miles and 385 yards, and in 1921 this was formally chosen by the IAAF as the standard length of a marathon.