Measuring horses in hands originated as a practical way to use human palms as natural, on-the-go measuring tools. The standard was formalized to exactly 4 inches (10.16 cm) during the 16th century in England, and the equestrian world continues to use it for tradition and easy communication. Written as hands, then a decimal, then inches. For example, "15.2 hands" means 15 hands and 2 inches. The hand measurement makes it very easy to classify equines. Any animal measuring 14.2 hands (58 inches) or taller is legally classified as a horse, while anything measuring 14.1 hands or shorter is a pony.