Interesting Facts About Noah’s Ark And The Flood A cubit is an ancient unit of measurement. One cubit is equivalent to an average adult human male’s arm, from the elbow to the tip of the middle finger (about 20 inches). It can vary though — one cubit can range from 15 to 22 inches. Pages: 1 2 3 4 5 6 7 8 9 10 11 12 13 14