The cubit is one of the oldest units of measure, employed as early as the Egyptian and Sumerian civilizations. Derived from the Latin word cubitus, this measure pertains to the lower arm, or to be more precise, the distance between the elbow and the tip of the outstretched middle finger. The exact measurement varies, though, since different types of cubits were used in Ancient Greece and Rome and throughout the Middle Ages up to the Early Modern Period.
The earliest known type of cubit was the royal cubit, which was used throughout the Egyptian dynastic period. It was roughly equivalent to 524 millimeters and was said to be employed in the construction of the Step Pyramid of the pharaoh Djoser in Saqqara.
The Roman cubitus is about 444.5 mm, with 24 cubitus equal to 35 English feet. The two types of Greek cubit are slightly longer; the Kyrenaika cubit measured 463.1 mm while the Metrios measured 474.2 mm. The Babylonians used the cubit of Lagash which was about 496.1 mm. They also had a trade cubit which was around nine-tenth of their normal cubit. Other measures of the cubit were from the Arabs, Mesopotamians, and Persians with lengths ranging from 370 mm to 650 mm.
The cubit was also extensively used in the Bible, particularly in the Old Testament. It was translated from the original Biblical Hebrew word pronounced as am-mah, which means the forearm. It was probably adopted from the Babylonians along with other Jewish units of measure. Also known as the ell, the cubit, as used by the ancient Hebrews, was equivalent to two spans or zeret with each span equal to three handbreadths or tefah and each handbreadth equal to four fingers (ezba). This was not always consistent, though, as the values of some of the cubits mentioned in Scriptures either deviate from this standard, such as those in the book of Ezekiel, or are still not known, like the unit of measure in Genesis.
The specific dimensions of Noah’s ark were expressed in cubits. The unit of measure was also used in describing the Ark of the Covenant built by Moses as well as the grand Jewish temple constructed during the time of King Solomon. Even the height of the infamous giant Philistine, Goliath, was given in cubits.
In the 20th century Burma, the cubit is recognized as a unit of length equivalent to 18 inches.