Deadweight tonnage (DWT)
Deadweight tonnage (DWT) measures a ship’s carrying capacity: the difference, in tonnes, between the vessel’s displacement when loaded to its maximum permitted draft and its lightship weight. It includes cargo, bunkers (fuel), fresh water, ballast, provisions, and crew — so the cargo a ship can actually lift is always somewhat less than its deadweight.
DWT is the standard way to describe the size of bulk carriers and tankers. The familiar market size classes are defined by deadweight:
- Handysize ~10,000–40,000 DWT and Supramax/Ultramax ~50,000–65,000 DWT
- Panamax/Kamsarmax ~65,000–85,000 DWT
- Capesize ~150,000–210,000 DWT (bulk); Aframax, Suezmax, and VLCC (~300,000 DWT) for tankers
Deadweight should not be confused with gross tonnage, which measures internal volume rather than weight, or with displacement, which is the total weight of the ship itself plus everything on board.