KM to miles converter

From Roman paces to a fixed metric ratio

Mile comes from the Latin mille passus, a thousand paces marked out by Roman armies. England later standardized its own version, the statute mile of 5,280 feet, by law in 1593. The kilometer is a purely metric unit, a thousand meters, with no older unit behind it.

The two were finally tied together exactly in 1959, when the mile was fixed at 1.609344 km, the same figure this converter uses.

Race distances in km and miles

A quick way to estimate without a calculator

• Multiply kilometers by 0.6 for a fast estimate. For 10 km: 10 x 0.6 is 6, close to the exact 6.21 miles.
• For a closer estimate over longer distances, multiply by 0.62 instead, which stays within about half a percent of the exact figure.
• For a 42.2 km marathon, the 0.62 version gives 26.16, very close to the commonly quoted 26.2 mile distance.

Common mistakes

• Assuming a "10K" race is 10 miles. The K stands for kilometers, so a 10K is 10 km, which is 6.21 miles.
• Using the quick 0.6 shortcut for a distance that needs to be exact, like a legal or scientific figure, instead of the true 0.6214 factor.
• Adding up rounded miles from several race legs instead of converting the total kilometers once, which drifts a little further from the exact figure with each rounded leg.