What is a cubic metre (CBM)?
A cubic metre is the three-dimensional space a shipment occupies. One CBM equals the volume of a cube one metre on each side, and in international transport it is usually called CBM (cubic metre). Sea and air freight rates are largely based on volume; road freight assesses volume together with weight and loading metres.
How is CBM calculated?
The formula is:
CBM = length (m) x width (m) x height (m) x quantity
If you measured in centimetres, convert to metres first (divide by 100), or multiply in centimetres and divide the result by 1,000,000.
Example: three cartons of 120 x 80 x 100 cm: 1.20 x 0.80 x 1.00 x 3 = 2.88 CBM.
Relation to volumetric weight
For light but bulky cargo carriers apply a "volumetric weight". Common conversions:
- Road and multimodal groupage: 1 CBM is roughly 333 kg
- Air freight: 1 CBM is roughly 167 kg (6,000 cm³ = 1 kg)
- Sea LCL: 1 CBM or 1,000 kg (the W/M rule, whichever is higher)
These ratios are common industry assumptions; the volume-to-weight conversion factor used for road groupage can vary by carrier, lane and tariff.
The invoice is based on the greater of the actual weight and the volumetric weight.
Which unit matters by mode?
| Transport mode | Governing unit |
|---|---|
| Sea LCL | CBM (W/M rule) |
| Air freight | Volumetric weight (CBM converted to kg) |
| Road groupage | Loading metres + CBM + tonnes |
| Road full load | Vehicle capacity (CBM / tonnes) |
Standard vehicle and container volumes
| Equipment | Approx. volume |
|---|---|
| Standard tilt trailer | ~90 CBM |
| Mega trailer | ~100 CBM |
| 20' standard container | ~33 CBM |
| 40' standard container | ~67 CBM |
| 40' high cube container (HC) | ~76 CBM |
Common mistakes
- Mixing centimetres and metres. This throws the result off by a factor of 1,000,000.
- Leaving out the pallet allowance. Add the pallet height (around 15 cm) to the total height for palletised cargo.
- Not measuring irregular cargo at its widest point.
- Forgetting to multiply by quantity.
Once you know the volume
If your cargo is stackable, the volume is a good starting point for groupage transport. If the volume approaches a vehicle's capacity, a full truck load is the better option. For all road options, see the international road transport page.
