High Quality Content by WIKIPEDIA articles! The hand is a non-SI unit of measurement of length, now used only for the measurement of the height of horses in some English-speaking countries, including Australia, Canada, the UK and the USA. With origins in ancient Egypt, it was originally based on the breadth of a human hand. It is today equal to four inches, and thus, following the adoption of the international inch in 1959, equal to exactly 10.16 centimetres. It may be abbreviated to "h" or the plural "hh". Although measurements between whole hands are usually expressed in what appears to be decimal format, the subdivision of the hand is not decimal but is in base 4, that is, subdivisions after the radix point are in quarters.