What is deadweight?
Deadweight (DWT) is the difference between a ship’s displacement at a given draft and the lightweight of the empty ship. It includes cargo, bunker, fresh water, stores, ballast and constant weights. Commercial officers talk about “available cargo deadweight” after deducting bunker, water, stores and ballast that must remain on board for the voyage.
How this calculator works
Total Deadweight = Displacement − Lightweight. Available Cargo DWT = Total Deadweight − Bunker − Fresh Water/Stores − Ballast. Displacement should be taken from the hydrostatic tables or deadweight scale for the current mean draft and water density. Lightweight is a fixed figure from the stability booklet. If cargo DWT comes out negative, one of the inputs is too high or the draft used for displacement is too light.
Who should use it
This page is useful for a quick cargo planning check. Official loading must still follow the load line, tank top strength, stability and the ship’s deadweight scale. Always confirm figures with the chief officer and the approved stability documents.