A hectometre (American spelling: hectometer, symbol hm) is a somewhat uncommonly used unit of length in the metric system, equal to one hundred metres. It derives from the Greek word "ekato", meaning "hundred".
For area the square hectometre (hm2) is a common unit. It is also known by the name hectare (ha), meaning 100 ares (100 a). The are is a measurement of area the size of 1 decametre by 1 decametre, which is 10 metres by 10 metres. Hence 100 are equals an area with dimensions 100 m by 100 m — 1 hectometre by 1 hectometre, the square hectometre — equalling 10,000 square metres (10,000 m2).
For volumes the cubic hectometre (hm3) is also used, 100 m by 100 m by 100 m equalling 1,000,000 cubic metres (1,000,000 m3).
