The sizes in our references range from the 17.5 inches per cubit that according to the World Almanac, is THE accepted standard, to 25.6 inches. I measured my own arm from the elbow to my index fingertip and it was 20.5 inches; I am 6 feet tall. Consider the arm length differences with a range of humans from a basketball player to a jockey... There may be a dispute over the actual value of a cubit but there is no doubt that Noah was quite a craftsman. Since this is an obscure area of science, for each value I made available, I had at least two independent verifications of validity. There may be more values (and probably are) but I could not find them and verify them. If you are aware of others and I can verify them, I would be happy to include them. If you wish to define your own value for cubits for your own calculation, select Create Your Own and insert the appropriate value in the adjacent field. That field is the equivalent for ONE (1) cubit.