Kilometre

The kilometre (written as km) is a way to measure distance. It is part of a special group of measuring tools called the International System of Units, and it equals one thousand metres. The word can also be spelled kilometer, especially in American English.

Most countries around the world use kilometres to talk about how far places are from each other. For example, when we say a city is 100 kilometres away, it means you would travel that many thousand metres to get there.

However, some countries like the United States and the United Kingdom use a different measurement called the statute mile instead of the kilometre. Still, the kilometre is very important for maps, science, and many everyday things where distance matters.

Pronunciation

There are two common ways to say the word "kilometre".

The first way puts the emphasis on the first syllable, like in words such as kilogram, kilojoule, and kilohertz. This is the way preferred by the British Broadcasting Corporation (BBC), the Canadian Broadcasting Corporation (CBC), and the Australian Broadcasting Corporation (ABC).

The second way puts the emphasis on the second syllable. This is common in places where the metric system isn’t used much. After Australia switched to the metric system in 1970, the government said the first way was official, but the prime minister at the time, Gough Whitlam, thought the second way was correct because of the word’s Greek roots.

Equivalence to other units of length

History

In 1790, French leaders asked scientists to create a new way to measure distance. They decided to use the distance from the North Pole to the Equator, and one metre was set as one ten-millionth of that distance. At first, the kilometre was called "Millaire," but another unit called the myriametre (10,000 metres) was more commonly used in France.

Other countries also started using the kilometre. The Netherlands adopted it in 1817, calling it "mijl." By 1935, the international group in charge of measurements officially stopped using the myriametre, making the kilometre the standard. Today, the symbol for kilometre is km.