Cubit

The cubit is a Biblical unit of measure. From Latin word cubitum meaning the elbow - the cubit was the average length of a man's arm from his elbow to the tip of his middle, or third, finger. It was a length equal to 17.5 inches or 444.5 mm.

Short Cubit
No international standard of the cubit exists today, as the cubit is not a modern unit of length and appears only in ancient documents.

In the re-establishment of civilization following the Global flood, various societies each defined the cubit according to its own rules and customs. Furthermore, both "short cubits" and "long cubits" are known to the Ancient Near East, especially in the very earliest of times (contemporary to Abraham).

The Hebrew cubit (אמח or ammah an arm) is today held to be the same as a Roman cubit as used by Flavius Josephus. In modern units this cubit measures 0.4445 meter. The best confirmation of the accuracy of this measurement is the Siloam Inscription at the entrance to Hezekiah's Tunnel in Jerusalem. It gives the length of the tunnel at 1200 cubits. Comparison of modern measurements with this dimension cannot yield an exact figure, but most scholars hold the approximate length of the tunnel, measured in modern units, as consistent with the definition of the Hebrew cubit as being the same as the Roman one.

Long Cubit
In 2004, and again in 2005, Tim Lovett speculated that the cubit used during the construction of Noah's ark was likely much longer. He cites the Sumerian and Egyptian Royal Cubits, both of which were longer than 0.445 meter. He eventually settles on the Royal Egyptian Cubit, which he affirms is the best-documented of the very ancient cubits, as the likely antediluvian cubit that Noah used to build his ark. This long cubit is 0.524 meter in length.

Implementation of the cubit on CreationWiki
In the length data type for semantic annotation (see Help:Semantic custom units), one meter is defined as 2.249718785 (short) cubits, the reciprocal relationship of one cubit being 0.4445 meter long. However, our length type also recognizes a long cubit of 0.524 meter and uses the ratio of 1 meter = 1.908396947 long cubits.