How to calculate CBM for shipping
CBM (cubic meter) is the basic unit of international freight. Suppliers quote it, forwarders price by it and container planning starts with it.
The formula
From centimeters
Most carton sizes are given in centimeters. Multiply the three sides and divide by 1,000,000. A carton of 60 × 40 × 50 cm is 120,000 cm³, or 0.12 CBM. One hundred cartons is 12 CBM.
From inches
Multiply the three sides in inches, then divide by 61,024. A 24 × 16 × 20 inch carton is 7,680 cubic inches, or about 0.126 CBM.
From meters
Just multiply. A pallet footprint of 1.2 × 1.0 m loaded to 1.5 m tall is 1.8 CBM.
How CBM is used in pricing
LCL sea freight
Less-than-container-load shipments are usually priced per CBM or per 1,000 kg, whichever is greater, with a one-CBM minimum. Light goods are priced on volume, dense goods on weight.
Air freight
Air freight uses chargeable weight. At the standard 1:6,000 ratio, 1 CBM counts as 166.67 kg. If your shipment weighs less than that per cubic meter, you pay for the volume.
How much fits in a container?
| Container | Internal volume | Realistic load |
|---|---|---|
| 20 ft standard | about 33 CBM | 25 to 28 CBM |
| 40 ft standard | about 67 CBM | 55 to 60 CBM |
| 40 ft high cube | about 76 CBM | 65 to 70 CBM |
Cartons never fill every gap, and door clearance and load shape reduce capacity further. As a rule of thumb, if an LCL shipment reaches around 13 to 15 CBM, get a quote for a full 20 ft container; it can work out cheaper.
Tips for accurate CBM
- Use the carton's outside dimensions, rounded up.
- For palletized goods, measure the loaded pallet, including the pallet and any overhang.
- Check supplier packing lists; carton sizes are sometimes listed from the product spec rather than measured.