Metre

:This article is about the unit of length. For other uses of metre or meter, see meter (disambiguation).

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The metre, or meter (symbol: m) is the SI base unit of length. It is defined as the length of the path travelled by light in absolute vacuum during a time interval of 1/299,792,458 of a second.

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Adding SI prefixes to metre creates multiples and submultiples; for example kilometre (1000 metres; kilo- = 1000) and nanometre (one billionth of a metre; nano- = 1 / 1 000 000 000).

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