1 mile = 1.609344 kilometres
Distance uses the same base unit as length but a different working range: road and marine measures at the small end, astronomical ones at the large. The nautical mile is not an imperial unit at all — it is defined as exactly 1852 metres, one minute of latitude, which is why it survives in aviation and shipping. At the far end, a parsec is roughly 3.26 light-years, and results that long switch to exponential notation.
Formula kilometres = miles × 1.609344
| Mile | Kilometre |
|---|---|
| 1 mi | 1.609344 km |
| 2 mi | 3.218688 km |
| 3 mi | 4.828032 km |
| 5 mi | 8.04672 km |
| 10 mi | 16.09344 km |
| 25 mi | 40.2336 km |
| 50 mi | 80.4672 km |
| 100 mi | 160.9344 km |
| 250 mi | 402.336 km |
| 500 mi | 804.672 km |
| 1000 mi | 1609.344 km |
Distance units follow the scale of the journey. Roads use kilometres in most countries and miles in the US and UK: a mile is exactly 1.609344 km, and 100 km is about 62 miles. At sea and in the air, distances are in nautical miles, which are exactly 1,852 m and roughly one minute of latitude, so a nautical mile is about 15 percent longer than a statute mile.
Space needs bigger units. The astronomical unit is the Earth-Sun distance, set at exactly 149,597,870.7 km, and light takes a little over eight minutes to cross it. A light-year is the distance light covers in a year, about 9.46 trillion kilometres. The nearest star beyond the Sun, Proxima Centauri, is about 4.2 light-years away.
To convert miles and kilometres in your head, multiply kilometres by 0.6, or miles by 1.6. For marine and aviation work, multiply nautical miles by 1.15 to get statute miles. The nautical miles and knots guide explains the units in more detail. For shorter measurements, see the length converter.
Related guides: Imperial vs metric: differences and quick conversion tricks