How to Convert Miles to Kilometers
A mile is 1,760 yards, and since 1959 a yard is exactly 0.9144 meters. Do the arithmetic — 1,760 × 0.9144 / 1,000 — and you get 1.609344 kilometers. That's the number. Not rounded, not approximated — it's the definitional consequence of the international yard. For most of history, the mile had dozens of competing definitions: the Roman mille passus (1,000 paces, about 1.48 km), the old London mile (~1.5 km), the Scots mile (~1.81 km). The 1959 international agreement swept all of that away. Today there's one statute mile, and it's 1.609344 km. The conversion is multiplication; the number is exact.
The Conversion Formula
km = miles × 1.609344
Worked Examples
Example 1: Convert 5 miles to kilometers
5 × 1.609344 = 8.04672 km (a 5-mile run is just over 8K)
Example 2: Convert 26.2 miles to kilometers
26.2 × 1.609344 = 42.165 km (the marathon — officially 42.195 km; 26.2 miles is a slight rounding)
Example 3: Convert 100 miles to kilometers
100 × 1.609344 = 160.934 km (an ultramarathon, and a common US-to-Canada border crossing leg)
Common Miles To Km Conversions
| miles | km |
|---|---|
| 1 mi | 1.609 km |
| 5 mi | 8.047 km |
| 10 mi | 16.093 km |
| 13.1 mi (half marathon) | 21.098 km |
| 26.2 mi (marathon) | 42.165 km |
| 50 mi | 80.467 km |
| 100 mi | 160.934 km |
Related Unit Converters
Frequently Asked Questions
How many kilometers are in a mile exactly?
1 mile = 1.609344 kilometers exactly. Fixed by the 1959 International Yard and Pound Agreement: 1 yard = 0.9144 meters, and 1 mile = 1,760 yards. The math: 1,760 × 0.9144 / 1,000 = 1.609344. Before 1959 the US Survey mile was about 1.609347 km — a difference of about 3 mm per mile, which accumulated to ~9.3 m over the US-Canada border and forced its formal deprecation in 2023.
How do I convert running pace from min/mile to min/km?
Divide by 1.609344. An 8:00 min/mile pace = 8.0 ÷ 1.609 = 4.97 min/km ≈ 4:58/km. Quick reference: 6:00/mi = 3:44/km, 7:00/mi = 4:21/km, 8:00/mi = 4:58/km, 9:00/mi = 5:36/km, 10:00/mi = 6:13/km. Most GPS watches let you switch the display — km splits give feedback twice as often as mile splits.
Why does the US still use miles on road signs?
Cost and public resistance. A brief 1970s metric highway experiment put dual-unit signs on a few Arizona and California highways — only Interstate 19's km markers survive today. The estimated $1.5+ billion cost to convert all 10+ million US road signs killed the program. Only three countries use miles on public roads: the US, the UK, and Liberia.
What's the difference between a nautical mile and a statute mile?
A nautical mile = 1.852 km = 1.1508 statute miles. It's one minute of latitude (1/60 of a degree) on any meridian — natural for chart navigation since you can read it directly off the latitude scale. A statute mile = 1.609 km. Confusing the two produces a 15% error: more than enough to miss an island or a fuel stop.
Engineering Context
The mile-to-kilometer conversion killed the US metric highway program in the 1970s, but Interstate 19 in Arizona is its living fossil. Running 101 km (63 miles) from Tucson to Nogales, I-19 was converted to km signage in 1980 as a demonstration project and never converted back. Six FHWA administrations and multiple Arizona DOT attempts to switch it to mileposts have failed — not because of engineering inertia, but because local businesses built their addresses, brochures, and delivery directions around the km exit numbers. Every exit sign is embedded in an ecosystem: GPS databases, emergency response maps, commercial delivery routes, real estate listings. Changing one sign means changing all of them. The engineering lesson: a unit standard, once baked into physical infrastructure and the economic activity around it, is vastly more expensive to change than the cost estimate for the signs alone would suggest.
More: km to miles · miles to meters · miles to feet · miles to nautical miles · Guide