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
Stowage factor and hold capacity
The stowage factor (SF) is the volume, in m³ or ft³, occupied by one tonne of cargo including the voids inherent to that cargo. Along with broken stowage — additional volume lost to hold shape, frames and hatch coamings — SF determines whether a bulk carrier's holds will "cube out" (run out of volume) before they "weight out" (reach the deadweight limit), or vice versa.
Dense cargoes such as iron ore or chrome ore weight out well before the holds are full, requiring alternate-hold loading or partial cargoes to respect tank-top strength limits. Light cargoes such as grain or wood pellets typically cube out first. This calculator compares the volume-limited and weight-limited tonnages against an intended cargo quantity to flag which constraint applies. Always confirm the shipper's IMSBC Code declaration for the actual parcel, as SF varies with sizing and moisture content.
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.