Digit (unit)

Detail of the Ancient Egyptian cubit rod in the Museo Egizio of Turin, showing digit, palm, hand and fist lengths

Some hand-based measurements, including the digit (6)

The digit or finger is an ancient and obsolete non-SI unit of measurement of length. It was originally based on the breadth of a human finger.^[1] It was a fundamental unit of length in the Ancient Egyptian, Mesopotamian, Hebrew, Ancient Greek and Roman systems of measurement.

In astronomy a digit is one twelfth of the diameter of the sun or the moon.^[2]

History[]

Ancient Egypt[]

The digit, also called a finger or fingerbreadth, is a unit of measurement originally based on the breadth of a human finger. In Ancient Egypt it was the basic unit of subdivision of the cubit.^[1]

On surviving Ancient Egyptian cubit-rods, the royal cubit is divided into seven palms of four digits or fingers each.^[3] The royal cubit measured approximately 525 mm,^[4] so the length of the ancient Egyptian digit was about 19 mm.

Ancient Egyptian units of length^[5]

Name	Egyptian name	Equivalent Egyptian values	Metric equivalent
Royal cubit	meh niswt	7 palms or 28 digits	525 mm
Fist		6 digits	108 mm
Hand		5 digits	94 mm
Palm	shesep	4 digits	75 mm
Digit	djeba	1/4 palm	19 mm

Mesopotamia[]

In the classical Akkadian Empire system instituted in about 2250 BC during the reign of Naram-Sin, the finger was one-thirtieth of a cubit length. The cubit was equivalent to approximately 497 mm, so the finger was equal to about 17 mm. Basic length was used in architecture and field division.