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Deadweight Tonnage Calculator

Work out deadweight tonnage instantly with clear inputs, formula shown and shareable results.

About Deadweight Tonnage Calculator

Deadweight is everything the ship can carry: loaded displacement minus lightship weight. It includes bunkers, stores, fresh water, crew and ballast as well as cargo, so cargo capacity is deadweight minus all of those — a distinction that matters on long voyages with heavy bunker loads.

Formula

Deadweight

DWT = loaded displacement - lightship; cargo = DWT - bunkers - stores - ballast

Worked example

With the default values below, Deadweight Tonnage Calculator returns Deadweight tonnage of 42,200.00. Change any input above and every figure here is recalculated in your browser.

Inputs used

Loaded displacement
52,000 t
Lightship weight
9,800 t
Bunkers, stores and fresh water
2,400 t
Ballast retained
600 t

Results

Deadweight tonnage
42,200.00 t
Cargo capacity
39,200.00 t
Lightship as share of displacement
18.8% %
Deadweight ratio
0.8115

Step by step

  1. 1Values used
  2. 2Deadweight
  3. 3Deadweight tonnage= 42,200.00 t
  4. 4Cargo capacity= 39,200.00 t
  5. 5Lightship as share of displacement= 18.8 %
  6. 6Deadweight ratio= 0.8115

Assumptions and limits

  • The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax or compounding frequency into account.
  • Figures are rounded for display to 4 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
  • Marine results are planning estimates only. Verify against the vessel's approved stability booklet, loading manual, class society rules and applicable maritime regulations before loading or sailing.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Marine results are planning estimates only. Verify against the vessel's approved stability booklet, loading manual, class society rules and applicable maritime regulations before loading or sailing.

Frequently Asked Questions

Is deadweight the same as cargo capacity?

No. Deadweight includes fuel, water, stores and crew. On a long voyage bunkers alone can absorb several percent of deadweight.

Why is deadweight quoted at summer draft?

Because that is the maximum permitted loading in normal conditions under the load line rules, giving a consistent basis for comparison.

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