A marathon is exactly 26.2 miles long, which is equivalent to 42.195 kilometers (or 26 miles and 385 yards). This distance has been the official standard for marathons since it was set by the International Amateur Athletic Federation (IAAF) in 1921, based on the length of the 1908 London Olympic marathon course
. The reason for this specific and somewhat unusual distance traces back to the 1908 London Olympics, where the race was extended to start at Windsor Castle and finish in front of the royal box at the Olympic stadium, resulting in the 26 miles and 385 yards length. Prior to that, marathon distances varied around 25 miles or roughly 40 kilometers
. In summary, the standardized marathon distance is:
- 26.2 miles
- 42.195 kilometers
- 26 miles and 385 yards
All official marathons worldwide adhere to this distance.
