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Free health tool

Distance Unit Converter

Express a known distance in kilometres or international miles using an exact unit definition.

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Original diagram of the same illustrative route expressed as 5.00 kilometres and 3.11 international miles, rounded to two decimals.

Calculate your result

Enter the distance number alone and choose its existing unit. Use a decimal point. This tool converts length, without estimating steps, pace or energy use.

Accepted range: 0 to 1000000 km

Your result will appear here

Nothing is saved or added to the URL.

What this result means

One international mile is exactly 1.609344 kilometres. Multiply miles by 1.609344 to get kilometres, or divide kilometres by 1.609344 to get miles. This converter rounds the result once to two decimals. [1][2]

An exact factor for a known length

NIST lists the international-foot-based mile as 1609.344 metres. The SI prefix kilo means one thousand, so this is exactly 1.609344 kilometres. The reverse calculation uses division by the same factor, without a separately rounded reciprocal. [1][3]

Check which kind of mile you have

This page uses international miles. Nautical miles and older U.S. survey-foot-based miles have different definitions. NIST distinguishes these units; a legacy land record or marine distance needs its correct definition rather than an assumed conversion. [1][2]

Rounding can prevent an exact round trip

For example, 5.00 kilometres displays as 3.11 miles. If you enter that rounded 3.11-mile result in the other direction, the display becomes 5.01 kilometres. The difference comes from rounding the intermediate value, rather than a change in length. Keep the original measurement when converting again.

A genuine zero displays 0.00. A positive result below the display resolution shows less than 0.01. More decimal places in a converted result do not mean the original route or device was measured more accurately.

Distance and pace are different questions

This tool restates an existing length. It does not infer distance from steps, calculate how long a trip takes, or turn a distance into an exercise recommendation. If your original value is in kilometres per hour, it is a speed rather than the length this page accepts.

Enter the number alone

Choose the input unit and enter a nonnegative number with a decimal point. Blank, negative, above-limit, unit-text, inequality, comma, fraction, scientific-notation and non-finite entries are rejected. The maximum is a software input limit, without a health meaning.

Share the page without sharing your entry

No account is required. Values remain in browser memory. Reset or reload clears the entry, and Share uses the clean page address. The optional recently-used list keeps a tool identifier, rather than your distance.

Formula and assumptions

Formula
kilometres = international miles Ă— 1.609344. international miles = kilometres Ă· 1.609344. [1][2][3]
Version
International mile and kilometre conversion, international-mile-km-1-609344-v1
Rounding
Use 25146/15625 and its exact reciprocal 15625/25146; round once to two decimals with halfway ties upward. Tiny positive results display a less-than sign.
Worked example
Example: 5.00 km ÷ 1.609344 = 3.106855961… mi, displayed as 3.11 mi. In the other direction, 1.00 mi × 1.609344 = 1.609344 km, displayed as 1.61 km. These are arithmetic examples, not recommended activity distances. [1]

Who this is for — and when not to use it

Intended use

Convert a known length between kilometres and international miles. Compare the units on a route, distance record or written measurement.

Not intended for

Convert nautical miles or historic U.S. survey miles. Estimate distance from steps, time, speed or personal stride length. Estimate calories, exercise benefit, pace or a personal activity target.

Exclusions

  • Different quantities such as speed, area or volume.
  • Nautical miles, historical survey-based units, inequalities or nonnumeric entries.

Evidence sources

  1. 1. Revised unit conversion factors: international foot-based mile — National Institute of Standards and Technology. Accessed Oct 8, 2026.
  2. 2. NIST SP 811: Guide for the Use of the International System of Units — National Institute of Standards and Technology. Accessed Oct 8, 2026.
  3. 3. SI prefixes: kilo means one thousand — International Bureau of Weights and Measures (BIPM). Accessed Oct 8, 2026.