In Genesis, the Ark’s three main dimensions were measured in cubits.
Genesis 6:15 specifies the Ark as 300 cubits long, 50 cubits wide, and 30 cubits high. A cubit was an ancient unit based broadly on the length of a forearm, so its exact modern equivalent varied by culture and period. That makes a precise conversion uncertain.
Using common estimates, the Ark would have been roughly 135 metres long, 22 metres wide, and 13 metres high, though translations and assumptions about the cubit produce different figures. The biblical text itself gives the dimensions, not a modern metric conversion.
The word “cubit” is also used in descriptions of other ancient structures, including parts of the Tabernacle and Solomon’s Temple. Readers sometimes mistake it for a fixed universal unit like a modern metre, but ancient cubits were not standardized globally. The dimensions therefore support a proportional description of the vessel more securely than an exact reconstruction.