Bulk Cargo Stowage Factor Calculator
Calculate maximum loadable tonnage from hold volume, stowage factor and broken stowage, and check whether an intended cargo quantity fits, using indicative IMSBC stowage factors.
Overview & methodology
Volume vs Weight Limits
Bulk carriers are subject to two primary constraints: volume (the physical space in the holds) and weight (the deadweight capacity of the vessel). Cargoes like Iron Ore are 'dense' and will cause a ship to reach its weight limit while the holds are still mostly empty. Conversely, light cargoes like Wood Pellets or Grain will 'cube out', filling the holds before the weight limit is reached.
Numerical Example: Grain Loading Example
Calculation: (20,000 × 0.98) / 1.35. The 2% broken stowage accounts for space lost at the top and corners of the hold.
Broken Stowage Explained
Broken stowage refers to the space in the hold that cannot be filled by cargo due to the ship's structural frames, pipes, and the angle of repose of the cargo. It is usually expressed as a percentage of the total hold volume and must be subtracted before applying the stowage factor.
Frequently asked questions
What is a stowage factor?
Stowage factor is the volume one tonne of cargo occupies, expressed in m³/MT or ft³/long ton (1 m³/MT ≈ 35.88 ft³/LT). Divide the available hold volume by the stowage factor to get the loadable tonnage before broken stowage.
How much broken stowage should I allow?
Free-flowing bulk such as iron ore fines or grain loses about 1–2% of hold volume; bagged cargo 10–15%; irregular or palletised cargo 15–25%. Deduct the broken-stowage percentage from hold volume before dividing by the stowage factor.