What does the miles to km converter do?
It turns a distance in miles into kilometers. Type 3.1 and you get 4.99 km. Type 26.2 and you get 42.16 km. The answer updates as you type, with no button to press.
The math is one multiplication: kilometers = miles × 1.609344. That factor is exact, not a measurement, so the converter uses all seven digits of it instead of a rounded 1.6. Under the kilometers you also get the same distance in meters and the same number read as a speed, because mph to km/h uses the identical factor.
People reach for it when a running plan, a US road map, a treadmill or a rental car speaks one unit and they think in the other. It works on any device and doesn't ask for anything but the number.
How to use the miles to km converter
- Type a distance in miles. Decimals work, so 13.1 and 0.25 are both fine.
- Read the kilometers on the result card. Results of 1 km or more show up to two decimals. Shorter ones show up to four, so 0.25 mi reads 0.4023 km.
- Check the lines below it: the distance in meters, and the speed version. Type 65 and you'll see 104.61 km, 104,607.36 m and 65 mph = 104.61 km/h.
- Copy the kilometers, or copy the whole formula line, such as
65 mi × 1.609344 = 104.61 km, to paste into a note or a message.
The converter won't take negative numbers and stops at one trillion miles. That's about 10,800 times the distance from Earth to the Sun, so you're unlikely to hit it.
The miles to km formula, and where 1.609344 comes from
A mile is 1,760 yards. Since 1959, a yard has been exactly 0.9144 meters, by an agreement between the US, the UK, Canada, Australia, New Zealand and South Africa. Multiply the two and you get the mile:
1,760 × 0.9144 m = 1,609.344 m = 1.609344 km
Nobody measures that number. It follows from the definitions, which is why it ends after six decimals. Going the other way, one kilometer is 1 ÷ 1.609344 = 0.621371 miles.
Worked example: a 5K
A running app says 3.1 miles. Multiply: 3.1 × 1.609344 = 4.9889664 km, which the converter shows as 4.99 km. That's 11 meters short of 5 km, because 3.1 is itself a rounded number. A true 5K is 3.10686 miles.
Doing it in your head
Multiply by 1.6: take the miles, add half, then add a tenth. 50 miles becomes 50 + 25 + 5 = 80 km. The real answer is 80.47 km, so the shortcut reads about 0.6% low. That's close enough for a road sign and too loose for a race distance.
Miles to kilometers conversion chart
These values come straight from the converter. The rounding matches what you'll see on the result card.
| Miles | Kilometers | Miles | Kilometers |
|---|---|---|---|
| 0.25 | 0.4023 | 20 | 32.19 |
| 0.5 | 0.8047 | 25 | 40.23 |
| 2 | 3.22 | 30 | 48.28 |
| 3 | 4.83 | 40 | 64.37 |
| 4 | 6.44 | 50 | 80.47 |
| 5 | 8.05 | 60 | 96.56 |
| 10 | 16.09 | 65 | 104.61 |
| 15 | 24.14 | 75 | 120.70 |
| 200 | 321.87 | 500 | 804.67 |
The tool itself shows 120.7 for 75 miles. It drops trailing zeros, so the table's 120.70 is the same value.
Race distances, both ways
Race courses are measured in kilometers, even in the US. Runners convert them to miles, round, and then convert back, which is where the small gaps come from:
| Race | Official distance | In miles | The rounded miles, converted back |
|---|---|---|---|
| 5K | 5 km | 3.107 mi | 3.1 mi = 4.99 km |
| 10K | 10 km | 6.214 mi | 6.2 mi = 9.98 km |
| Half marathon | 21.0975 km | 13.109 mi | 13.1 mi = 21.08 km |
| Marathon | 42.195 km | 26.219 mi | 26.2 mi = 42.16 km |
For pace per mile or per kilometer, the running pace calculator picks up where this leaves off.
Which mile? Statute, survey and nautical
"Mile" has meant several lengths. Put the wrong one in and the answer will be off.
| Mile | Length | Where you'll see it |
|---|---|---|
| Statute (international) mile | 1.609344 km exactly (5,280 ft) | Road signs, maps, running, car odometers. This is the one the converter uses. |
| US survey mile | about 1.609347 km | Older US land surveys. Retired by NIST at the end of 2022, and only 3.2 mm longer per mile. |
| Nautical mile | 1.852 km exactly | Ships and aircraft. Knots are nautical miles per hour. |
| Roman mile | about 1.48 km | History books. It was 1,000 paces, and gave the mile its name. |
The survey mile differs by two parts in a million, so you can ignore it unless you're reading an old property deed. The nautical mile is the real trap. It's 15% longer than a land mile, so typing nautical miles into a land-mile converter gives an answer about 13% too low.
Common mistakes when converting miles to km
- Converting the wrong direction. Miles to km makes the number bigger (× 1.609). Km to miles makes it smaller (× 0.621). If 10 miles came out as 6.2, you divided. For that direction, use the km to miles converter.
- Using 1.6 over long distances. 1.6 is 0.6% short. Over a 400-mile drive, that's 640 km instead of 643.74 km, a 3.7 km gap.
- Rounding twice. Round only at the end. 3.1 miles is already a rounded 5K, so converting it back gives 4.99 km, not 5.
- Mixing up speed and distance. The number converts the same way, but the units don't mix. 60 mph is 96.56 km/h, not 96.56 km. For other speed conversions, the km/h to mph converter covers the reverse.
Converting feet, yards or inches instead? The length converter handles every length unit in one place.
Frequently asked questions
How do I convert km back to miles?
Divide by 1.609344, or multiply by 0.621371. So 5 km is 3.107 miles, 4.99 km is 3.10 miles and 3.7 km is 2.30 miles.
How many km is 100 miles?
160.93 km. A 100-mile bike ride, often called a century, is just under 161 km. A metric century is 100 km, or 62.14 miles.
How many meters are in a mile?
1,609.344 meters exactly. The converter shows it on the meters line as 1,609.34 m, rounded to two decimals.
Is 1.6 close enough for converting miles to km?
For directions, a road sign or a rough training plan, yes. It reads about 0.6% short, which is 6 meters per kilometer. For a race distance, a fuel calculation or anything you'll add up over many trips, use the full 1.609344.
Why does 26.2 miles give 42.16 km and not 42.195 km?
Because 26.2 is a rounded number. The marathon is 42.195 km, which is 26.219 miles. Dropping the last part of the miles drops about 30 meters from the converted distance.
Can I type a speed instead of a distance?
Yes. Type the mph number as if it were miles and read the speed line. 70 gives 70 mph = 112.65 km/h.