What is a stowage factor?

Stowage factor (SF) is the volume in cubic metres that one metric tonne of a particular cargo occupies when stowed, expressed as m³/t. It combines the density of the commodity itself with the irregular shape and packing voids. A low SF (e.g., iron ore 0.35 m³/t) means very dense cargo; a high SF (e.g., timber 2.0 m³/t) means bulky, lightweight cargo. Planners use SF to determine whether a hold is weight-limited or volume-limited.

What is broken stowage and what are typical values?

Broken stowage is the wasted space between packages, at hold frames, behind stanchions, and at the ends of rows — expressed as a percentage of the gross hold volume. Typical values: general cargo (boxes, crates) 10–20%, bagged cargo 5–10%, bales 8–15%, bulk grain or ore 0–3%, containers in a cell-guide hold 2–5%. The calculator default of 5% is conservative for bagged or palletised cargo.

How does IMSBC differ from commercial stowage factors?

The IMSBC Code (IMO MSC.354(92)) lists individual solid bulk cargoes with their bulk density, angle of repose, and moisture limits, but does not always provide SF in m³/t directly. Commercial SFs quoted by shippers are typically based on stowed volume including packing, whereas IMSBC bulk density figures are for the cargo in isolation. For IMSBC cargoes, use the listed bulk density to derive SF = 1 ÷ bulk density (t/m³).

When is a hold weight-limited versus volume-limited?

A hold is weight-limited when the cargo density is so high that the mass reaches the structural deadweight limit before the hold volume is filled — common for iron ore, steel, and heavy aggregates. It is volume-limited when the cargo is light or bulky and fills the hold space before reaching deadweight — common for grain, timber, and containers with light stuffing. Planners must solve for the binding constraint for each hold.

Stowage factor calculator

Volume needed = cargo mass × stowage factor × (1 + broken stowage %). Select a common commodity or enter a custom factor. Optionally enter the hold grain volume to see utilisation percentage.

Cargo mass (tonnes)

Commodity / stowage factor (m³/t)

Broken stowage (%)

Typical: bulk 0–3%, bagged 5–10%, general 10–20%.

Hold grain volume (m³) — optional

Leave blank to skip utilisation check.

Result

Volume needed: 6825.0 m³

Notes & caveats

· Stowage factors in the preset list are representative commercial values. Actual SF may vary by variety, moisture content, and packing method — obtain the shipper's certificate of stowage factor for each parcel.
· For IMSBC Code cargoes, bulk density (t/m³) is listed in individual schedules. SF = 1 ÷ bulk density. Confirm with the shipper's declaration and cargo information form required by SOLAS VI/2 and IMSBC 4.2.
· Hold grain volume vs. bale volume: grain volume includes all curved surfaces and hatch coaming space; bale volume excludes frames and obstructions. Use the correct figure from the vessel's capacity plan.
· Containers (33 m³/TEU) is a nominal average; actual container internal volume is 33.2 m³ for a standard 20-foot dry box. High-cube units provide 37.9 m³.

Sources: IMSBC Code (IMO MSC.354(92)); SOLAS Chapter VI; IACS; see also CSS Code lashing force calculator, ballast exchange calculator, stowage factor glossary.