How to convert kilometers to miles: formula and examples

Quick answer: the formula

To convert kilometers to miles, divide the distance by 1.609344. To convert in the opposite direction, multiply the number of miles by the same factor.

miles = kilometers / 1.609344
kilometers = miles × 1.609344

These formulas use the international statute mile (mi). The conversion factor published by the National Institute of Standards and Technology establishes that one mile equals 1.609344 km.

Three quick references:

• 10 km = 6.213711... mi ≈ 6.21 mi.
• 10 mi = 16.09344 km ≈ 16.09 km.
• 5 km = 3.106855... mi ≈ 3.11 mi.

For more values without calculating each one, see the kilometers-to-miles table for common distances.

If you only need the result, use the kilometers and miles converter and choose how many decimal places to display.

How to convert kilometers to miles

The process has three steps:

1. Identify the distance in kilometers.
2. Divide that value by 1.609344.
3. Round the result only at the end.

For example, to convert 10 km:

10 / 1.609344 = 6.213711...

Rounded to two decimal places:

10 km ≈ 6.21 mi

You can also multiply the kilometers by the inverse factor:

miles = kilometers × 0.621371192237...

Both methods produce the same result. Dividing by 1.609344 is often easier to remember because it starts with the exact equivalence of one mile.

How to convert miles to kilometers

To convert statute miles to kilometers, multiply by 1.609344.

For example, to convert 10 mi:

10 × 1.609344 = 16.09344

Rounded to two decimal places:

10 mi ≈ 16.09 km

The multiplication works the same way with decimal values. For 2.5 mi:

2.5 × 1.609344 = 4.02336 km

Therefore, 2.5 mi is approximately 4.02 km.

Worked examples

Convert 5 kilometers to miles

Divide 5 by the conversion factor:

5 / 1.609344 = 3.106855...

The result is:

5 km ≈ 3.11 mi

This is the familiar equivalent of a 5K race.

Convert 42.195 kilometers to miles

The official marathon distance, 42.195 km, converts as follows:

42.195 / 1.609344 = 26.218757...

Rounded to two decimal places:

42.195 km ≈ 26.22 mi

The guide to pace per kilometer and pace per mile explains how to convert time per unit of distance.

Convert 60 miles to kilometers

Multiply 60 by the factor:

60 × 1.609344 = 96.56064

Therefore:

60 mi ≈ 96.56 km

When to round the result

Two decimal places are usually enough for travel, races and everyday references. The right precision still depends on the use:

• One or two decimal places may be enough for a mental estimate.
• Two decimal places are usually clear for a route or sports distance.
• When chaining calculations, keep all available decimals and round the final result.
• For technical work, use the precision required by the procedure or data source.

Rounding too early can accumulate differences. Using 0.62 as an approximate factor is practical, but it should not replace 0.621371192237... when the distance is large or the calculation requires greater precision.

Decimal points and decimal commas

English-language tools usually write one and a half kilometers as 1.5 km, while other regional settings may display 1,5 km. Both expressions represent the same quantity; only the writing convention changes.

Before pasting a number into a spreadsheet or app, check which decimal separator it accepts. The site converter can interpret examples such as 10.5 km or 6.2 mi, but other systems depend on their regional settings.

Distance is not the same as speed

Kilometers and miles measure distance. Kilometers per hour and miles per hour measure speed.

The numerical factor between km/h and mph is the same because both speeds use one hour as their time base, but they describe a different quantity. Do not drop /h or treat a speed as though it were a distance.

For more context about where each unit appears on roads, maps and in sports, see kilometers vs. miles.

How to estimate mentally

For a quick reference, multiply the kilometers by 0.62:

20 km × 0.62 ≈ 12.4 mi

Another option is to divide by 1.6:

20 km / 1.6 ≈ 12.5 mi

These are estimates, not exact conversions. Using the full factor, 20 km is approximately 12.43 mi.

Convert a distance with the calculator

The formula is useful when you want to understand the process or repeat it by hand. When you need to check a value, reverse the conversion direction or select the precision, use the kilometers-to-miles calculator.

You can enter an amount with its unit, swap km and mi, copy the result and review the formula used.

Frequently asked questions

How many miles are in 1 kilometer?

One kilometer is approximately 0.621371 mi. Rounded to two decimal places, 1 km ≈ 0.62 mi.

How many kilometers are in 1 mile?

One international statute mile equals 1.609344 km.

How can I convert kilometers to miles mentally?

Multiply the kilometers by 0.62 or divide by 1.6 for a quick estimate. Use the full factor when you need a more precise result.

Is a statute mile the same as a nautical mile?

No. The statute mile used in this conversion equals 1.609344 km; a nautical mile equals 1.852 km and is used mainly in maritime and air navigation.

Should I always round to two decimal places?

Not necessarily. Two decimal places are practical for most everyday uses, but keep more precision in technical calculations or when the result will be used in another operation.

Sources

1. NIST Guide to the SI, Appendix B.9: Conversion Factors · National Institute of Standards and Technology · Accessed July 27, 2026
2. Marathon · World Athletics · Accessed July 27, 2026