An aircraft runs out of space long before it runs out of lift, so airlines charge for whichever is greater: what your shipment weighs or the space it occupies. The conversion between space and weight is the volumetric divisor, and understanding it is the difference between a quotation that holds and one that doubles at the terminal.
The calculation
Measure each piece at its widest point, including the pallet, skid and any overhang. Multiply length by width by height in centimetres and divide by the applicable divisor to obtain volumetric weight in kilograms. Compare it with the actual gross weight; the higher figure is your chargeable weight. Airlines then round the result — commonly up to the next 0.5 kg.
| Service | Divisor (cm³ per kg) | Equivalent density |
|---|---|---|
| IATA general air cargo | 6000 | 167 kg per CBM |
| Express courier | 5000 | 200 kg per CBM |
| Some domestic / charter contracts | 4000–4500 | 222–250 kg per CBM |
Worked example, metric
Three cartons of 120 × 80 × 90 cm, gross weight 95 kg each. Volume per carton is 864,000 cm³; divided by 6000 that is 144 kg volumetric against 95 kg actual. The chargeable weight is therefore 144 kg per carton, or 432 kg for the shipment — 137 kg more than the scale shows.
Worked example, inches
Working in inches, multiply length × width × height and divide by 366 for the 6000 divisor, or by 305 for the 5000 divisor. A 48 × 40 × 45 inch skid is 86,400 cubic inches, which is 236 kg volumetric on the air cargo basis.
Cutting a dimensional penalty
- Reduce height first — it is usually the dimension with the most slack once cartons are stacked and shrink-wrapped.
- Avoid overhang. Anything projecting past the pallet edge is measured, and it can also disqualify the piece from a lower-deck position.
- Nest and knock down where the product allows; a disassembled frame can halve volumetric weight.
- Consolidate several small parcels into one well-built skid instead of shipping loose cartons at courier divisors.
- For light bulky cargo, ask about the airline's density-based or pivot-weight contract rates before defaulting to a general cargo rate.
The terminal re-measures. Declare the dimensions you actually shipped, including pallet and wrap, or expect a re-weigh correction on the invoice.
Frequently asked questions
Why is the courier divisor 5000 instead of 6000?
Integrators run tighter density economics on their networks, so they price space more aggressively. The same box costs 20% more in chargeable weight terms with a 5000 divisor.
Is the pallet included in the measurement?
Yes. Both the pallet's footprint and its height are measured, and its weight counts towards the gross weight.
Can chargeable weight be lower than actual weight?
No. It is always the greater of actual and volumetric weight, so dense cargo simply pays on its actual weight.
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