The basic unit of length in the International System of Units.
Properties
- One metre is equal to 10 decimetres, 100 centimetres and 1000 millimetres.
- One kilometre is equal to 1000 metres.
Notations
The multiples of the metre are :
- the decametre : 1 dam = 10 m
- the hectometre : 1 hm = 100 m
- the kilometre : 1 km = 1 000 m
- the megametre : 1 Mm = 106 m
- the gigametre : 1 Gm = 109 m
- the terametre : 1 Tm = 1012 m
- the petametre : 1 Pm = 1015 m
- the exametre : 1 Em = 1018 m
- the zettametre : 1 Zm = 1021 m
- the yottametre : 1 Ym = 1024 m
The submultiples of the metre are :
- the decimetre : 1 dm = 0,1 m
- the centimetre : 1 cm = 0,01 m
- the millimetre : 1 mm = 0,001 m
- the micrometre : 1 µm = 10-6 m
- the nanometre : 1nm = 10-9 m
- the picometre : 1 pm = 10-12 m
- the femtometre : 1 fm = 10-15 m
- the attometre : 1 am = 10-18 m
- the zeptometre : 1 zm = 10-21 m
- the yoctometre : 1 ym = 10-24 m
Educational note
The value of the metre is based on a universal constant, the speed of light in a vacuum. It corresponds to the length of the path travelled by light in a vacuum during a time interval of \(\frac{1}{299\space 792\space 458}\) of a second.
Until 1960, the metre was defined as a length equal to one ten-millionth of the length of a quadrant along the Earth’s meridian.