Lengths in the Bible can be confusing when ancient measures are used. The Old Testament uses the following lengths.
|Biblical unit||Approximate metric equivalent|
These are based on body parts. The cubit was originally the length of the forearm, and the span was the width of fingers spread out. Over time, these became standardized to specific lengths, although the exact lengths varied between locations. Hence, the Egyptian cubit is shorter than the Hebrew cubit. There was also a long cubit consisting of a cubit and a hand-breadth (Ezekiel 40:5), or about 56cm.
In the New Testament, several longer measures were also used. These are usually better known by the names they were given in the King James Version.
|Biblical unit||KJV name||Approximate metric equivalent|
These are not exactly the same length as the fathom, furlong and mile in common use. Most modern versions replace these lengths with modern equivalents.
The new Jerusalem described in Revelation 21 was shaped like a cube with sides of length 12,000 stadia (Revelation 21:16). That is, 2200 kilometres or nearly 1400 miles. Its walls were 144 cubits thick (69 metres or 226 feet). These huge lengths provide a hint that the city should be interpreted figuratively rather than literally.
For a detailed discussion of these ancient measurement systems, see the Wikipedia articles: