The hand is a non- SI unit of length equal to exactly 4 inches (101.6 mm). It is normally used to measure the height of horses in some English-speaking countries, including Australia, Canada, Ireland, the United Kingdom, and the United States. It is customary when measuring in hands to use a point to indicate inches (quarter-hands) and not tenths of a hand. For example, 15.1 hands normally means 15 hands, 1 inch (5 ft 1 in), rather than 15 + 1 ⁄ 10 hands.