公引，又称粨（（英式英文：hectometre、美式英文：hectometer），记号hm）是国际单位制之一，为「百」和「米」的合字，即100公尺；此单位现已较少使用。

The hectometre (International spelling as used by the International Bureau of Weights and Measures; SI symbol: hm) or hectometer (American spelling) is an uncommonly used unit of length in the metric system, equal to one hundred metres. It derives from the Greek word "ekato", meaning "hundred". A regulation football or soccer field is approximately 1 hectometre in length.