Gross register tonnage (GRT, grt, g.r.t., gt) or gross registered tonnage, is a ship's total internal volume expressed in "register tons", each of which is equal to 100 cubic feet (2.83 m3). Gross register tonnage uses the total permanently enclosed capacity of the vessel as its basis for volume. Typically this is used for dockage fees, canal transit fees, and similar purposes where it is appropriate to charge based on the size of the entire vessel.