# Metre

A **metre** (US spelling, *meter*) is the basic unit of length in the SI measurement system. The symbol for the metre is **m**. The first meaning (in the French Revolution) was one ten-millionth of the distance between the Earth's equator and the North Pole along the Paris meridian.^{[1]} The metre is now defined as the distance light travels in a vacuum in 1/299,792,458 of a second.^{[1]}

In the imperial system of measurement, one yard is 0.9144 metres (after international agreement in 1959), so a metre is very near to 39.37 inches: about 3.281 feet, or 1.0936 yards.

## Units multiples

- 0.000 000 000 000 000 000 000 001 Ym (yotametre) = 1 m
- 0.000 000 000 000 000 000 001 Zm (zetametre) = 1 m
- 0.000 000 000 000 000 001 Em (exametre) = 1 m
- 0.000 000 000 000 001 Pm (petametre) = 1 m
- 0.000 000 000 001 Tm (terametre) = 1 m
- 0.000 000 001 Gm (gigametre) = 1 m
- 0.000 001 Mm (megametre) = 1 m
- 0.001 km (kilometre) = 1 m
- 0.01 hm (hectometre) = 1 m
- 0.1 dam(decametre) = 1 m
- 1 m (metre)
- 10 dm (decimetres) = 1 m
- 100 cm (centimetres) = 1 m
- 1000 mm (millimetres) = 1 m
- 1 000 000 μm (micrometres) = 1 m
- 1 000 000 000 nm (nanometres) = 1 m
- 1 000 000 000 000 pm (picometres) = 1 m
- 1 000 000 000 000 000 fm (fermi or femtometres) = 1 m
- 1 000 000 000 000 000 000 am (attometres) = 1 m
- 1 000 000 000 000 000 000 000 zm (zeptometres) = 1 m
- 1 000 000 000 000 000 000 000 000 ym (yoctometres) = 1 m

## Metre Media

Gravimeter with variant of Repsold-Bessel pendulum.

Triangulation near New York City, 1817

Ibáñez apparatus calibrated on the metric Spanish Standard and used at Aarberg in canton of Bern, Switzerland.

Closeup of National Prototype Meter Bar No. 27, made in 1889 by the International Bureau of Weights and Measures (BIPM) and given to the United States, which served as the standard for defining all units of length in the US from 1893 to 1960. In 1960 the SI changed the standard of length to define the meter by the wavelength of light of a spectral line of

## Related pages

## References

- ↑
^{1.0}^{1.1}"Historical context of the SI". US Government - National Institute of Standards and Technology.