A hand is the unit of measurement the is used to measure a horse. One hand equal to four inches. You measure from the ground to the withers.If a horse is said to be 16 hands, that means 16x 4 = the horse is 64" tall. Sometimes you will see the height as 15.1 or 16.3. That decimal point refers to the extra inch or extra 3 inches that do not even out to the full 4 inches of a hand. So a horse that is 15.1 would be 15x4 = 60" + 1" = 61" tall.