Kilometres to Metres Converter
This calculator converts between kilometres and metres instantly, using the exact SI definition that 1 kilometre equals 1,000 metres, so you get a precise result every time rather than an estimate. Type a value into either the kilometres field or the metres field and the other field updates immediately, which makes it useful for running and cycling distances, road and travel distances, physics and engineering calculations, and mapping, surveying or construction work where plans mix the two units. You can also pick a common distance from the preset dropdown, including 1 metre, 100 metres, 500 metres, 1 kilometre, a mile (1.609 km), 5 km, 10 km, a half marathon (21.0975 km), a full marathon (42.195 km) and 100 km, and the calculator fills in the kilometres field and converts automatically. Results are shown for kilometres, metres and centimetres in the results bar, with the full conversion, including millimetres, repeated in the detail boxes alongside a worked example and the formula used, kilometres multiplied by 1,000. Below the calculator you will find a reference table of common km to m conversions at a glance, plus notes on how the metric prefix system works. Because the conversion is defined exactly, with no rounding involved, you can rely on the figures for scientific work as well as everyday distance conversions.
Convert Kilometres to Metres
Convert Metres to Kilometres
Type in either field. Editing kilometres updates metres and vice versa.
Common km to m Reference
| Kilometres (km) | Metres (m) | Centimetres (cm) | Millimetres (mm) |
|---|---|---|---|
| 0.001 km | 1 m | 100 cm | 1,000 mm |
| 0.01 km | 10 m | 1,000 cm | 10,000 mm |
| 0.1 km | 100 m | 10,000 cm | 100,000 mm |
| 0.5 km | 500 m | 50,000 cm | 500,000 mm |
| 1 km | 1,000 m | 100,000 cm | 1,000,000 mm |
| 5 km | 5,000 m | 500,000 cm | 5,000,000 mm |
| 10 km | 10,000 m | 1,000,000 cm | 10,000,000 mm |
| 42.195 km | 42,195 m | 4,219,500 cm | 42,195,000 mm |
| 100 km | 100,000 m | 10,000,000 cm | 100,000,000 mm |
Your Conversion
Worked Example
How to Convert Kilometres to Metres
The conversion between kilometres and metres is exact and always the same: multiply kilometres by 1,000 to get metres. This follows directly from the SI prefix system, where "kilo" means one thousand. So 1 kilometre is defined as exactly 1,000 metres, 2 km is 2,000 m, 0.5 km is 500 m, and so on.
To go the other way (metres to kilometres), divide by 1,000. For example, 750 m divided by 1,000 = 0.75 km.
The Formula
| Direction | Formula | Example |
|---|---|---|
| Kilometres to metres | m = km × 1,000 | 3.5 km × 1,000 = 3,500 m |
| Metres to kilometres | km = m ÷ 1,000 | 4,200 m ÷ 1,000 = 4.2 km |
Why the km and m Units Exist
The metre was defined in 1799 as part of the French metric system that eventually became the International System of Units (SI). The kilometre was introduced as a convenient multiple for measuring longer distances such as road lengths, geographic features, and travel distances. In New Zealand and most countries worldwide, road signs, speed limits, and distances are expressed in kilometres. Scientific and engineering measurements often require the base unit, metres.
Common Uses of km to m Conversion
- Running and cycling events: a 5 km run is 5,000 m; a 10 km race is 10,000 m
- Road distances: a 2.5 km stretch is 2,500 m
- Physics and engineering: velocity, acceleration, and many formulas require SI base units (metres, not kilometres)
- Mapping and surveying: converting GPS coordinates or contour intervals
- Construction: site plans often use metres while road specifications use kilometres
The SI Metric Prefix Ladder
| Unit | Symbol | Relation to 1 metre |
|---|---|---|
| Kilometre | km | 1,000 m |
| Metre | m | 1 m (base unit) |
| Centimetre | cm | 0.01 m |
| Millimetre | mm | 0.001 m |
| Micrometre | um | 0.000001 m |
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Sources and method: International Bureau of Weights and Measures (BIPM), The International System of Units (SI), 9th edition (2019). The conversion 1 km = 1,000 m is exact by definition with no rounding error.
This converter uses the exact SI definition: 1 kilometre = 1,000 metres. Results are mathematically precise. For scientific calculations requiring significant figures, apply appropriate rounding to your input values.