Chargeable Weight Explained: Why Air and Express Bills on Volume, Not Just Kilos
Air and express carriers bill on chargeable weight, which is the greater of your shipment's actual gross weight and its volumetric (dimensional) weight. Volumetric weight is calculated from the package dimensions: for air freight the standard is length x width x height in centimetres divided by 6000, while express couriers often use 5000; 1 CBM of space is treated as 167 kg. A light, bulky carton can therefore be billed on its size, not its kilos. To control cost, reduce dimensions (smaller cartons, tighter palletizing), keep actual weight low, and compare the chargeable weight your forwarder calculates before booking. Sea LCL instead bills on the greater of CBM and weight tons, so the same box is measured differently by mode.
- Chargeable weight = the higher of actual gross weight and volumetric weight.
- Air freight volumetric weight typically uses divide-by-6000; express couriers often divide-by-5000.
- 1 CBM is treated as 167 kg for air; the same carton is measured differently by sea LCL.
- Bulky, light cargo is usually billed on volume, so pack denser to cut cost.
- Always ask your forwarder for the chargeable weight, not just the kilos, before booking air or express.
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Why weight alone is not what you pay for
Aircraft and vans are limited by both weight and the physical space a shipment occupies. A pallet of foam cushions may weigh little but fill a volume that could otherwise carry dense metal parts. Carriers therefore charge on chargeable weight — the higher of what the goods actually weigh and what their volume 'weighs' under a standard formula. This protects carriers from losing money on bulky, light cargo.
The volumetric formula
For air freight the usual rule is: volumetric weight (kg) = (length x width x height in cm) / 6000. Express couriers (DHL, FedEx, UPS) frequently use /5000, which produces a higher volumetric weight and therefore a higher bill for the same box. Always confirm which divisor your carrier applies. The CBM convention ties the two worlds together: 1 CBM of air cargo is treated as 167 kg (1000 / 6), so a 2 CBM consignment has a volumetric weight of about 334 kg even if it physically weighs 120 kg.
Worked example
A carton measuring 60 x 50 x 40 cm = 120,000 cm3. Divided by 6000 that is 20 kg volumetric weight. If the carton actually weighs 8 kg, the carrier bills 20 kg (the greater). Ten such cartons bill as 200 kg, not 80 kg. The same cartons by LCL sea would bill on CBM (0.12 CBM each, 1.2 CBM total) against weight tons, often cheaper for non-urgent freight.
Air versus express versus sea
Air freight and express both use volumetric weight; the difference is the divisor (6000 vs 5000) and the service level. Sea LCL does not use the /6000 rule at all — it bills on the greater of CBM and weight tons, so the same bulky carton is measured by volume in cubic metres, not by an artificial 'kg' conversion. This is why switching a light, bulky shipment from air to sea can cut the freight bill sharply, at the cost of transit time.
| Mode | Billing basis | Example 1.2 CBM / 96 kg |
|---|---|---|
| Air freight (/6000) | Greater of kg and CBMx167 | Bills ~200 kg (volumetric) |
| Express (/5000) | Greater of kg and CBMx200 | Bills ~240 kg (volumetric) |
| Sea LCL | Greater of CBM and weight tons | Bills 1.2 CBM |
How to reduce chargeable weight
- Use the smallest carton that protects the product; oversized boxes inflate volumetric weight.
- Stack and palletize tightly so the measured cuboid wastes less air.
- Negotiate carton dimensions with the supplier before production, not after.
- Compare actual vs volumetric at the quote stage and challenge mismeasurement.
- For recurring shipments, standardize carton sizes to predictable chargeable weights.
Common mistakes
- Quoting a customer on 'gross weight' and then being billed on volumetric weight.
- Assuming express and air use the same divisor — they often do not.
- Forgetting that dimensional weight applies per piece, so odd-shaped cartons add up.
- Not measuring the final, taped carton (stretch wrap and pallet add volume).
Next steps
Measure every carton's final dimensions and weight, calculate both actual and volumetric weight, and request the chargeable weight from your forwarder before booking. Our chargeable weight calculator does the comparison for air versus LCL so you can see which mode is cheaper for your box.