Convert kilometer to mile.

About this conversion

Kilometers-to-miles: multiply by 0.621371. Used whenever you need to express metric distances in imperial terms, especially for US audiences or in car specs.

Formula

mi = km × 0.621371

Real-world examples

Reference values

Tips & tricks

• Mental shortcut: multiply by 0.6. 100 km ≈ 60 mi.
• Speed limits: 100 km/h ≈ 62 mph (typical European highway); 120 km/h ≈ 75 mph (German autobahn off-limit zone).
• A 5K race is a common entry-level run distance, equivalent to 3.1 miles.

Origin & history

See the inverse (mi → km) for history.

What is a kilometer?

One kilometer equals exactly 1,000 meters. Road distances, geographic distances, marathon running, and everyday long-distance measurement worldwide except in the US, UK and a few other countries.

What is a mile?

The international (statute) mile equals exactly 1,609.344 meters or 5,280 feet. Road distances and speed limits in the US, UK, and a handful of other countries.

What does ,400 km look like in everyday objects?

Some everyday comparisons can make the unit easier to picture.

• 384,400 km — roughly the distance from Earth to the Moon.
• 1 km — about the length of 10 city blocks in Manhattan.
• 5 km — about a 30-minute easy run.

How to convert kilometer to mile

To convert a value from kilometer (km) to mile (mi), apply the conversion factor shown in the formula above. The calculation is the same whether you do it by hand, in a spreadsheet, or with the live converter on this page.

Steps:

1. Take your input value in km.
2. Apply the formula see formula above.
3. The result is your value in mi.

For repeated calculations, save the formula in a spreadsheet or use the live converter at the top of this page — it handles the math automatically and displays the result as you type.

Frequently asked questions

How do I convert km to mi?

Apply the formula km → mi shown above, or just type your value into the converter at the top of this page. The result updates instantly.

Which is bigger, km or mi?

This depends on the conversion ratio in the formula. If the factor multiplied by your value gives a larger number, then mi is the smaller unit (so it takes more of them to express the same quantity). If the result is smaller, then mi is the larger unit.

When would I use km versus mi?

Both units measure length, so the choice depends on context. Kilometer is typically used for engineering specs, construction, navigation, and everyday measurement; mile similarly. Most professional fields standardize on one or the other based on regional conventions or technical tradition.

How precise is this km to mi conversion?

The conversion factor shown is the internationally defined exact value (or the best-published approximation if the relationship is irrational, like degrees-to-radians). The live converter on this page uses double-precision floating-point math, accurate to about 15 significant digits — far beyond any practical engineering need.

Is the conversion ratio exact, or an approximation?

Most unit conversions between SI metric units, and between SI and US customary units, have been formally defined as exact values since the 1959 international yard-pound agreement and subsequent SI redefinitions. Exceptions are unit pairs that involve irrational numbers (radians, e.g.) or empirical conversions (like food calories, which depend on temperature). When in doubt, consult the formula at the top of this page.

Related conversions

See also