Ans

Unit converter

Kilometres to metres.

Convert km to m and m to km. Type in either box and the other follows. A thousand metres to the kilometre, which is what the prefix means.

km → mExact definition
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Kilometres to metres — common values, to 6 significant figures.
kmm
0.5 km500 m
1 km1000 m
2 km2000 m
5 km5000 m
10 km10000 m
21.0975 km21097.5 m
42.195 km42195 m
100 km100000 m
1 km=1000 m 1 m=0.001 km

Definitions

  • The kilometre is a thousand metres, and the unit road distances are signed in almost everywhere except the UK and the US.
  • The metre is the SI base unit of length, defined by fixing the speed of light at 299 792 458 m/s.
  • This conversion is exact by definition. 1 km = 1000 m.
  • The metre is SI; every imperial and US customary length here is defined exactly in terms of it by the 1959 international yard and pound agreement.

How it works

One direction multiplies and the other divides by the same number, so nothing is lost by going back and forth.

The value passes through m, the unit every other length & distance unit on the site is defined against, rather than a number written into this page on its own. That is why the figure here, the figure in the table above and the general length & distance converter always agree.

Display precision limits significant figures rather than decimal places, because one fixed number of decimals is useless across a range this wide. Very large and very small results switch to scientific notation with a proper superscript exponent. The editable box always holds a plain number at full working precision, so you can carry on from either side.

Common questions this answers: how many metres in a kilometre (1000), how many kilometres in a metre (0.001), and what 5 km is in metres (5000 m).

From the maker of Ans — a scientific calculator you can own. Same idea: a proper instrument, nothing in the way.