Miles into kilometers
Going from miles to kilometers means multiplying by one fixed number: 1.609344. That’s the exact definition of a mile in metric terms, set by the 1959 international agreement. No rounding baked into it. A mile is a fair bit longer than a kilometer, so every mile figure grows by roughly 60% when you convert.
Type miles in, read kilometers out, live as you type. The calculation runs in your browser, which means nothing uploads and there’s no server delay.
Road trips across the border
Planning a drive into a metric country and your map app or odometer reads miles? This is the conversion you want. A 250-mile leg becomes 402.3 km, which matters when fuel stops and signage are all metric. “Next services 45 miles” is 72.4 km, so you know how far you can push before refueling.
Speed flips too. If you’re used to a 70 mph highway, that’s 112.7 km/h, right around the typical European motorway limit. A 30 mph town speed is 48.3 km/h. Knowing this keeps you from misreading the dashboard when you cross over.
Marathons and long runs
Distance running mixes the two systems constantly. A marathon, which most people know as 26.2 miles, is 42.16 km by that rounded figure (the official course is 42.195 km). A half marathon at 13.1 miles is 21.08 km. Even a casual benchmark like a 5-mile run converts to 8.05 km, handy if your training app logs in kilometers but your route was measured in miles.
Ultras get wild here. A 100-mile race is 160.93 km, and seeing it in kilometers really drives home the scale of the thing.
Reference distances:
- 1 mi = 1.609344 km
- 5 mi = 8.04672 km
- 13.1 mi = 21.08 km (half marathon)
- 26.2 mi = 42.16 km (marathon)
- 100 mi = 160.934 km
How to use it
Enter miles in the input field and the kilometer value updates live, no button to press. The dropdown lets you change either unit, so flipping to kilometers-to-miles or switching distance units stays right here. A reference table sits below for the common values, including race distances and round numbers.
Display rounds to a sensible precision. Since the mile is exactly 1.609344 km, you can always work from that exact factor when you need more decimal places.
Questions people ask
How many km in a mile?
1.609344 kilometers, exactly. A bit over one and a half. For a fast estimate, multiply miles by 1.6.
What’s 5 miles in km?
8.047 km. Multiply 5 by 1.609344. A common running and walking distance.
How long is a marathon in km?
42.195 km officially. The “26.2 miles” everyone quotes is that distance rounded, and 26.2 miles converts back to about 42.16 km.
Is 1.609344 exact or approximate?
Exact. The international mile was defined as precisely 1,609.344 meters in 1959. Every miles-to-km conversion comes from that figure.
How do I convert mph to km/h?
Same factor: multiply the speed in mph by 1.609344. So 60 mph is 96.6 km/h, and 80 mph is 128.7 km/h.
Does my input get sent anywhere?
No. The conversion is browser-side JavaScript, so it runs offline once loaded and your numbers stay on your device.