Horses are measured from the ground to the top of the withers. The withers is the highest point of the back. It is created by the vertebrae between the shoulder blades.

Traditionally, horses are measured in "hands." One horse hand (or hh) is 4 inches long (10 centimeters). It's about the width of a man's fist. So 1 1/4 hands is written 1.1 hands, while 1 3/4 hands is written 1.3 hands.

One of the tallest breeds, the Shire, can reach 19 hands high (76 inches, or 193 centimeters). Miniature horses can be as small as 5 hands high (20 inches, or 51 centimeters).