Calculate stowage factor from cargo volume and weight, convert it between m³/t and ft³/long ton, or find hold volume or cargo weight for typical cargoes.
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Stowage Factor Formula
The stowage factor tells you how much space a cargo occupies for each unit of weight. It is a core planning metric in shipping, warehousing, and freight loading because it shows whether a cargo is likely to be limited by available space or by allowable weight.
In general, stowage factor is volume divided by weight on the same shipment basis; its numeric value depends on the chosen units. The formulas below use base cargo volume before any separately added allowance. In this calculator, an additional broken-stowage percentage b is measured against base cargo volume: total cargo-space volume = base volume × (1 + b/100). The base factor is therefore total cargo-space volume ÷ [weight × (1 + b/100)]; the effective factor including the allowance is base factor × (1 + b/100). If a supplied factor already includes the relevant gaps, leave the extra allowance blank or enter 0 to avoid double counting.
Variables
| Variable | Description | Typical Units |
|---|---|---|
| SF | Stowage factor | ft³/lb, ft³/short ton, ft³/long ton, m³/kg, m³/metric ton |
| V | Base cargo volume, excluding any separately added broken-stowage allowance | ft³, m³, L |
| W | Cargo weight on the same shipment basis as the base volume | lb, kg, short ton, metric ton |
Common Unit Forms
| Output Unit | Formula | Notes |
|---|---|---|
| ft³/lb | SFft³ / lb = Vft³ / Wlb |
Direct imperial volume-per-pound result |
| ft³/short ton | SFft³ / short ton = Vft³ × 2000 / Wlb |
Uses 1 short ton = 2,000 lb |
| ft³/long ton | SFft³ / long ton = Vft³ × 2240 / Wlb |
Common maritime convention |
| m³/kg | SFm³ / kg = Vm³ / Wkg |
Direct metric volume-per-kilogram result |
| m³/metric ton | SFm³ / metric ton = Vm³ × 1000 / Wkg |
Uses 1 metric ton = 1,000 kg |
How to Calculate Stowage Factor
- For a factor or weight solve, enter total available cargo-space volume. For a volume solve, enter cargo weight and pick a typical cargo or enter the base stowage factor. To convert units, choose Convert stowage factor units.
- Determine the total cargo weight using the same shipment basis.
- Select the unit system you want for the answer.
- Set a separate extra-space allowance only when needed: b is a nonnegative percentage of base cargo volume, not a fraction of the hold. Blank means 0; a collapsed entered allowance remains active.
- Select Calculate and review base factor, effective factor and the base/extra/total volume breakdown. Check actual allowable weights and operational limits separately.
A higher stowage factor means the cargo is bulkier for its weight and will consume more space. A lower stowage factor means the cargo is denser and will consume less space per unit of weight.
Example
If a shipment has a total cargo volume of 300 ft³ and a total cargo weight of 5,000 lb, the direct imperial stowage factor in cubic feet per pound is:
If you want the answer in cubic feet per short ton:
If you want the answer in cubic feet per long ton:
Why Stowage Factor Matters
- Load planning: Estimates a volume requirement or a volume-based cargo weight; it does not check geometry, securing, vessel stability or allowable loads.
- Space vs. weight limits: Compare the volume-model result against separately established weight limits; this calculator does not determine those limits.
- Cargo comparison: Makes it easier to compare dense and lightweight goods on a consistent basis.
- Freight efficiency: Supports better packing, stacking, and equipment selection.
Practical Notes
- The calculator automatically normalizes its listed volume, weight and factor units. For a manual formula, convert units consistently and keep the shipment basis matched.
- Match volume and weight definitions for packaging, pallets, dunnage and handling materials. Count relevant occupied space or gaps once, either in the supplied factor or a separate allowance.
- For mixed cargo, use total combined volume divided by total combined weight to get the shipment-level stowage factor.
- If cargo settles, compresses, or expands in transit, the effective stowage factor can change.
- Be careful with the word ton; short ton, long ton, and metric ton are different units.
Common Mistakes
- Using mismatched units in a manual formula, or choosing a wrong unit label in the calculator even though its listed unit conversions are automatic.
- Using net product weight but gross loaded volume.
- Confusing short tons with long tons in maritime calculations.
- Entering a very small weight with a large volume and misreading the result due to unit selection.
