The kilometre is the common unit of longer distances on Earth. The SI unit is the metre and a kilometre is 1000 metres. It is now used more often than miles for measuring road distance. It is also more used more often than the nautical mile for sea distances and air distances. However in the UK and the USA, the mile is used more than kilometres.
It is often used to measure the speed of cars, planes and boats by saying how many kilometres it can travel in an hour. This is shown as km/h.
It is also spelled kilometer. This spelling is used in American English.
One kilometre is 0.6214 miles (3280.84 feet). This means that one mile is 1.6093 kilometres.