Net Tonnage (NT)

(0.2+0.02 log10(Vc)) Vc (4d/3D)2, for passenger ships the following formula is added: 1.25 (GT+10000)/10000 (N1+(N2/10)), where Vc is the volume of cargo holds, D is the distance between ship's bottom and the uppermost deck, d is the draught N1 is the number of cabin passengers, and N2 is the number of deck passengers.) "Ton" is figured as an 100 cubic foot ton.

Source: U.S. Maritime Administration.