There is no direct mathematical relationship between these tonnages whereby with the aid of multipliers you can convert one to the other. However, formula do contain some empirical conversion formulae arrived at by statistical analysis. These will give approximate solutions for typical ships: for example, the relationship between net tonnage, gross and deadweight tonnages for a typical traditional cargo ship is such that if net tonnage were one unit its gross tonnage might be 1.5 units and the deadweight 2–2.5 units. Note, however, that with different ship types and sizes these relationships vary.
