Convert between different units of length including metric and imperial measurements such as meters, kilometers, feet, inches, yards, and more.
The meter was originally defined in 1793 as one ten-millionth of the distance from the equator to the North Pole. Today, it's defined by the distance light travels in a vacuum during a specific fraction of a second.
Only three countries in the world officially use the imperial system: the United States, Liberia, and Myanmar. The rest of the world primarily uses the metric system.
The standard marathon distance of 26.2 miles (42.195 kilometers) was established at the 1908 London Olympics. The course was extended so the race could finish in front of the royal family's viewing box.
A nautical mile is based on the circumference of the Earth and is equal to one minute of latitude. It's approximately 1.15 standard miles or 1.85 kilometers and is used for air and sea navigation.