How this calculator works
The kilometre is a decimal multiple of the metre, defined by the SI prefix kilo for one thousand. Converting kilometres to metres is therefore a multiplication by 1,000 with no rounding. The same factor connects every metric length unit: a kilometre is 100,000 cm or 1,000,000 mm. The mile and foot rows use the international definitions, where one mile is exactly 1,609.344 m.
Formula
m = km x 1,000. km = m / 1,000. 1 km = 100,000 cm = 1,000,000 mm. 1 mi = 1.609344 km and 1 ft = 0.3048 m.
Worked example
1 km = 1,000 m. 0.5 km = 500 m. 2.5 km = 2,500 m. 42.195 km = 42,195 m, the marathon distance. 10 km = 10,000 m.
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Frequently asked questions
Is a kilometre 1,000 metres by definition?
Yes. The kilo prefix means one thousand, and the metre is the SI base unit of length. No measurement or rounding is involved.
How many metres are in a marathon?
A marathon is 42.195 km, which is 42,195 m. Half a marathon is 21.0975 km, or 21,097.5 m.
Why do maps show kilometres but building plans show metres?
Kilometres keep large distances short to write, while metres match the scale of buildings and rooms. Both are metric, so moving between them only shifts the decimal point.
How does a kilometre compare with a mile?
One mile is exactly 1.609344 km, so 1 km is about 0.621371 mi. A 10 km race is about 6.21371 mi.