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Block Coefficient Calculator

Work out block coefficient instantly with clear inputs, formula shown and shareable results.

About Block Coefficient Calculator

Block coefficient is the ratio of the actual underwater volume to the box that just encloses it: Cb = volume / (L x B x T). Full hulls near 0.85 carry the most cargo for their dimensions, while fine hulls near 0.55 make less wave resistance and are used where speed matters.

Formula

Block coefficient

Cb = displaced volume / (L x B x T)

Worked example

With the default values below, Block Coefficient Calculator returns Block coefficient of 0.7194. Change any input above and every figure here is recalculated in your browser.

Inputs used

Displaced volume
10,100 m³
Length on waterline
120 m
Beam
18 m
Draft
6.5 m

Results

Block coefficient
0.7194
Enclosing box volume
14,040 m³
Indicated hull type
Moderate form (general cargo)
Displacement in sea water
10,352.50 t

Step by step

  1. 1Values used
  2. 2Block coefficient
  3. 3Block coefficient= 0.7194
  4. 4Enclosing box volume= 14,040 m³
  5. 5Indicated hull type= Moderate form (general cargo)
  6. 6Displacement in sea water= 10,352.50 t

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, fees or charges 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

What is a typical Cb?

About 0.80-0.87 for tankers and bulkers, 0.60-0.70 for general cargo ships, 0.55-0.65 for container ships and below 0.5 for fast craft.

How does Cb relate to speed?

Full hulls make large wave systems, so they are economical only at low Froude numbers. Fine hulls trade cargo volume for lower resistance at speed.

Related Calculators

Block Coefficient Calculator – Calculate Block coefficient