What is a cubit?

In ancient Egypt and Mesopotamia, the basic unit of length was the cubit, based on a forearm measured from the elbow to the tip of the outstretched middle finger. Indeed, the word cubit comes from the Latin word cubitum, meaning “elbow.” This distance is approximately 18 inches (roughly 45 centimeters). In ancient times, the cubit was usually defined as equal to 24 digits or 6 palms. The Egyptian “royal” or “long” cubit, however, was equal to 28 digits or 7 palms.