A horse length, or simply length, is a unit of measurement that refers to the length of a horse from nose to tail, approximately 8 feet,[1] It is commonly used in Thoroughbred horse racing, where it describes the distance between horses in a race. Horses may be described as winning by several lengths, as in the notable example of Secretariat, who won the Belmont Stakes by 31 lengths (248 feet (76 m)) More often winning distances are merely a fraction of a length, such as half a length. Distances smaller than that are similarly described in reference to the equine body with terms such as a "neck", a "head", a "short head", a "nose" or "the slimmest fraction of a nose."
These terms are used in other disciplines of equestrianism as well, particularly useful as a guide for riders in spacing animals apart when a number of them are all together in a riding arena, such as during group riding instruction or at a horse show.
Harness race finishing margins are typically measured in meters etc.