How many miles is 1 kilometer?

1 kilometer equals approximately 0.621371 miles. To convert km to miles, multiply by 0.621371 or divide by 1.60934.

How many kilometers is 1 mile?

1 mile equals approximately 1.60934 kilometers. To convert miles to km, multiply by 1.60934.

Why does the US use miles instead of kilometers?

The US established its measurement system before the metric system became widespread. While most countries adopted metric in the 19th-20th centuries, the US retained customary units due to the cost of conversion and cultural familiarity.

Kilometers to Miles Converter

Convert kilometers to miles instantly with our free online calculator. Whether you're tracking running distances, planning road trips, or converting international measurements, this tool provides accurate conversions.

Conversion Formula

Conversion	Formula	Example
km to miles	km × 0.621371	10 km = 6.21 miles
miles to km	miles × 1.60934	10 miles = 16.09 km

Quick Reference Table

Kilometers	Miles	Common Use
1 km	0.62 mi	Short walk
5 km	3.11 mi	5K race distance
10 km	6.21 mi	10K race distance
21.1 km	13.1 mi	Half marathon
42.2 km	26.2 mi	Full marathon
100 km	62.14 mi	Long driving distance

Why the Difference?

The kilometer is based on the metric system (1/10,000 of the distance from Earth's equator to the North Pole), while the mile has Roman origins (1,000 paces). The metric system is used in most countries, while the US, UK (for roads), and a few others use miles.

Running Pace Conversion

Pace (min/km)	Pace (min/mile)
4:00	6:26
5:00	8:03
6:00	9:39
7:00	11:16

Conversion Code Example

``javascript function kmToMiles(km) { return km * 0.621371; }

function milesToKm(miles) { return miles * 1.60934; }

// Examples console.log(kmToMiles(10)); // 6.21371 console.log(milesToKm(10)); // 16.0934``

Country Usage

System	Countries
Metric (km)	Most of the world
Imperial (miles)	USA, Liberia, Myanmar
Mixed	UK (miles for roads, km for other)

Use this converter for accurate distance conversions between metric and imperial systems.

How Many Decimals Do You Need?

Rounding the factor costs accuracy, and how much depends on the factor. Converting 137 km with the factor truncated at each decimal place:

Decimals kept	Factor	137 km becomes	Error
0	1	137	60.9344%
1	0.6	82.2	3.4394%
2	0.62	84.94	0.2207%
3	0.621	85.077	0.0597%
4	0.6214	85.1318	0.0046%

A rule that holds for any conversion: round once, at the end. Rounding the factor and then multiplying compounds the error through every subsequent calculation, while carrying full precision and rounding the final answer does not.

The right number of significant figures is set by your input, not by the converter. If you measured kilometers to three significant figures, the answer in miles is only good to three — writing more digits claims precision the measurement never had.

Other Conversions From Kilometers

The same value in every other unit this converter supports for length:

From	To	Unit
1 km	1,000 m	Meters
1 km	100,000 cm	Centimeters
1 km	1,000,000 mm	Millimeters
1 km	1,093.61 yd	Yards
1 km	3,280.84 ft	Feet
1 km	39,370.08 in	Inches
1 km	0.539957 nmi	Nautical Miles

Chaining conversions works — kilometers to metres to feet gives the same answer as kilometers to feet — but each step rounds, so a chain of three conversions carries three roundings. Convert directly where a direct factor exists.

Kilometers to Miles Converter