Stowage factor explained: formula, conversion and typical values
Two cargoes of the same weight can need very different ships. Stowage factor tells you how much space each tonne takes, which decides whether a ship will fill its holds before it reaches its deadweight, or the other way round.
What stowage factor means
Stowage factor (SF) is the volume one tonne of cargo occupies in a ship's hold, including the spaces between particles. It is quoted in cubic metres per metric tonne (m³/mt) or in cubic feet per tonne (cft/mt). A low stowage factor means a dense cargo, such as iron ore. A high one means a light, bulky cargo, such as barley or woodchips.
Converting between units
1 m³ = 35.315 cubic feet, so 1 m³/mt = 35.315 cft/mt. To convert cft/mt to m³/mt, divide by 35.315. For example, 47 cft/mt ÷ 35.315 = 1.33 m³/mt.
Typical stowage factors
| Cargo | m³/mt (approx.) | cft/mt (approx.) |
|---|---|---|
| Iron ore | 0.35 to 0.50 | 12 to 18 |
| Clinker | 0.65 to 0.80 | 23 to 28 |
| Cement (bulk) | 0.70 to 0.90 | 25 to 32 |
| Wheat | 1.25 to 1.35 | 44 to 48 |
| Coal | 1.15 to 1.40 | 41 to 49 |
| Corn (maize) | 1.35 to 1.45 | 48 to 51 |
| Urea (bulk) | 1.35 to 1.45 | 48 to 51 |
| Barley | 1.45 to 1.60 | 51 to 56 |
Checking whether a cargo fits
Multiply the quantity by the stowage factor to get the space the cargo needs, and compare it with the ship's grain capacity (for bulk) or bale capacity (for packaged cargo).
Example: 30,000 mt of wheat at 1.30 m³/mt needs 39,000 m³. A ship with 42,000 m³ grain capacity has the space. The same ship with barley at 1.55 m³/mt could carry only about 27,000 mt before its holds are full, well below its deadweight. The ship has 'cubed out'.
Cubing out and weighing out
- Light cargo (high SF): the holds fill first, so the ship cubes out below its deadweight
- Dense cargo (low SF): the ship reaches its deadweight with space left, so it weighs out
- Dense cargoes also need care with hold loading limits and alternate-hold loading
- Tolerance on quantity (for example 10% more or less) should be checked at both ends of the range
How we use stowage factor
When a cargo is entered on our desk, its stowage factor is normalised to m³/mt and checked against each candidate ship's grain or bale capacity, using the worst case of the quantity tolerance. A ship that cannot take the full stem is marked as not fitting, with the numbers shown, before any offer goes out.
Frequently asked questions
- What is the stowage factor of wheat?
- Roughly 1.25 to 1.35 m³/mt, or about 44 to 48 cft/mt, depending on the grade and moisture. Always use the shipper's declared figure.
- How do I convert stowage factor from cft to m³?
- Divide the figure in cubic feet per tonne by 35.315. For example, 50 cft/mt is about 1.42 m³/mt.
- What is the difference between grain and bale capacity?
- Grain capacity is the hold volume available to a free-flowing bulk cargo, including the spaces between frames. Bale capacity is the smaller volume available to packaged cargo such as bags or bales.
Where this applies on our desk: Scrap shipping, Northern Europe to Türkiye scrap and Black Sea to Türkiye grain.