How is a meter calculated?

Answer 1

It was originally determined to be 1/10,000,000 of the distance from the equator to the north or south pole. That's why it is easy to remember that the circumference of the earth is 40,000,000 meters, or 40,000 km.

Answer 2

The meter has quite a history. It arose out of changes in France after the revolution of the 1780's. The first definition in 1790 was the length of a pendulum with a half period of 1 second. In 1791 this was changed to be one ten-millionth of the distance from the equator to the north pole (through Paris of course). In 1799 a platinum bar became the standard, held in Paris. In 1889 the first General Conference on Weights and Measures defined a bar of platinum/iridium alloy, held at the melting point of ice. In 1960 this deinition was changed to be based on the wavelength of radiation from krypton 86.

The current definition is based on the speed of light in a vacuum: one meter is the distance covered by light in 1/299,792,458 of a second, in a vacuum.

For practical purposes, standard bars are kept in various places including in the US

Answer 3

The answer that was previously here was offensive and off subject.

Answer 4

It is calculated in the SI system as the distance light travels in a vacuum in 1/299,792,458 of a second.