How do I convert miles to km?

Multiply the mile value by 1.609344. One mile is defined as exactly 1.609344 kilometers, so 10 miles × 1.609344 = 16.09 km. To go the other way, divide kilometers by 1.609344 (or multiply by 0.621371). The converter does both directions for you — type in either field and the other updates instantly.

How many miles is a 5K, 10K, half marathon and marathon?

A 5K is about 3.11 miles and a 10K about 6.21 miles. A half marathon (21.0975 km) is about 13.11 miles, and a full marathon (42.195 km) is about 26.22 miles — usually quoted as 13.1 and 26.2 miles. Type any race distance into the converter to see it in the other unit.

Does this also work for mph to km/h?

Yes — speed uses the same factor because the hour is identical on both sides. 60 mph × 1.609344 = 96.56 km/h, and 100 km/h ÷ 1.609344 = 62.14 mph. Just enter the speed number and read the result as per-hour.

Is this converter free and private?

Yes. The maths runs entirely in your browser with plain JavaScript — nothing you type is uploaded, stored or shared, there's no account and no usage limit. It also keeps working offline once the page has loaded.

Converters

Miles to KM Converter

Convert miles to kilometers (and back) instantly — with race distances, the exact formula and a reference table.

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Common values

Miles

Kilometers

Type in either field — the other converts live. 1 mile = 1.609344 km exactly.

Result

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Enter a value in Miles or Kilometers

How the conversion works

The mile is defined as exactly 1.609344 kilometers, so the conversion is a single multiplication or division:

miles → km: multiply by 1.609344 — 10 mi × 1.609344 = 16.0934 km
km → miles: divide by 1.609344 — 42.195 km ÷ 1.609344 = 26.2188 mi

There is no rounding hidden in the factor itself: 1.609344 follows directly from the inch being fixed at 25.4 mm in 1959 (1 mile = 63,360 inches), so results are as exact as the number of decimals you keep.

Quick reference table

Miles	Kilometers
1 mi	1.61 km
2 mi	3.22 km
3.1 mi	4.99 km (≈ 5K race)
5 mi	8.05 km
6.2 mi	9.98 km (≈ 10K race)
10 mi	16.09 km
13.1 mi	21.08 km (half marathon)
20 mi	32.19 km
26.2 mi	42.16 km (marathon)
100 mi	160.93 km

How to use it

Type a distance into either field — miles or kilometers.
The other side converts live; results are trimmed to four decimals.
Tap a common value chip (1, 3.1, 5, 10, 13.1, 26.2, 100 mi) to jump straight to typical road and race distances.
Copy puts the full conversion (e.g. 26.2 mi = 42.1648 km) on your clipboard.

When you need this

Race distances and training plans, road-trip planning between countries, reading a US car's odometer in metric, speed limits when driving abroad (the same factor works for mph ↔ km/h) — anything that crosses between metric and imperial distances. If you're converting a race distance, the Pace Calculator turns it straight into split times. For lengths the CM to Inches Converter works exactly the same way, and the general Unit Converter covers weight, volume, temperature and more in one place.

Private by design

The conversion runs in your browser — nothing is uploaded or tracked, and there's no sign-up. Browse more free utilities on the all tools page.

Frequently asked questions

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