CBM stands for cubic metre. In shipping and warehousing it is the volume a carton, a pallet or a whole shipment takes up. One CBM is a space of 1 metre by 1 metre by 1 metre. Suppliers, forwarders and warehouse teams all use it to compare shipments, plan space and check what a container can take.
The CBM formula
For one carton or package, convert each side to metres and multiply:
CBM = length (m) × width (m) × height (m)
If your measurements are in centimetres, multiply them together and divide by 1,000,000. If they are in millimetres, divide by 1,000,000,000. If they are in inches, multiply them together and divide by 61,024.
For the whole shipment, multiply the CBM of one carton by the number of cartons:
Total CBM = CBM of one carton × number of cartons
Worked example
A carton measures 60 cm × 40 cm × 30 cm.
- In metres: 0.60 × 0.40 × 0.30 = 0.072 CBM for one carton.
- The delivery has 500 cartons: 0.072 × 500 = 36 CBM in total.
Use the outside dimensions of the carton as delivered, including any bulge, strapping or protruding corners, not the size printed on the product specification.
The mistakes seen most often
- Wrong dimensions. Using the product size, the inner size, or a dimension copied from an old document instead of measuring the carton that arrived.
- Forgetting the quantity. Calculating one carton correctly and stopping there.
- Confusing one carton with the shipment. The CBM of one carton and the total shipment CBM are very different numbers, and mixing them up on a document is easy to miss.
- Mixed units. Multiplying centimetres by metres, or forgetting to divide by 1,000,000 after multiplying centimetres.
From CBM to pallets
Total CBM tells you how much volume the cartons have. It does not tell you how many pallets you will build. A pallet has a fixed footprint, a height limit and a weight limit, and cartons only fit in whole numbers. Cartons per layer, how the cartons are turned on the pallet, the number of layers, the height your racking or vehicle allows and the pallet’s weight limit all decide how much of the theoretical volume you actually use.
Example: a pallet of 1200 × 1000 mm and cartons of 400 × 300 × 300 mm. Nine cartons fit in a layer (3 × 3, with 100 mm left over on the 1000 mm side). Five layers is 45 cartons and 1,650 mm high including a 150 mm pallet. The cartons hold 45 × 0.036 = 1.62 CBM, but the space the loaded pallet occupies is 1.2 × 1.0 × 1.65 = 1.98 CBM. About 82% of the space is carton volume, and the rest is unused because of the pallet and layer pattern. Planning on CBM alone would under-count the space you need. The guide to standard pallet sizes lists the common pallet footprints and the weight and height limits to check.
The same happens in a container. The theoretical CBM of the cartons is a maximum, not a promise. Pallet dimensions, carton dimensions, the loading pattern, weight limits, room for handling, stacking restrictions and the need to keep the load stable all reduce what really fits. That is why a container is rarely filled to its full CBM. The table below gives the internal volume of the common containers.
How many CBM fit in a 20ft or 40ft container?
Internal sizes vary a little between container owners, so check the figures for your own container. The guide to how many CBM fit in a container gives the published sizes and tested loads for six carton sizes. These are typical values:
| Container | Internal size (L × W × H) | Internal volume | Typical loadable CBM, loose cartons |
|---|---|---|---|
| 20ft | 5,898 × 2,352 × 2,393 mm | about 33.2 CBM | about 25 to 28 CBM |
| 40ft | 12,032 × 2,352 × 2,393 mm | about 67.7 CBM | about 55 to 58 CBM |
| 40ft High Cube | 12,032 × 2,352 × 2,698 mm | about 76.4 CBM | about 65 to 68 CBM |
The loadable figure is lower than the internal volume for the reasons above: whole cartons, gaps at the walls and under the roof, room to load, and stacking limits. On pallets the usable volume is lower again. The weight can also run out before the space does, so check the payload of the container and the road weight limits for heavy goods.
A shipment well below a full container, for example 2 to 12 CBM, usually goes as LCL (less than container load, in a shared container) and is charged per CBM or per tonne. Ask your forwarder at what volume a full 20ft becomes the cheaper option.
To check a real shipment, use the CBM Calculator for cartons of several sizes, or the Container Loading Calculator for pallets.
How CBM relates to freight charges
Whether a forwarder charges by volume, by weight, or by the container depends on the transport mode and on the forwarder’s terms. Air freight normally uses a chargeable weight, which is the greater of actual weight and volumetric weight. Sea freight is often quoted per container or, for smaller shipments, per CBM or per tonne. Always check your forwarder’s rate sheet or quotation rather than assuming one method.
Use the calculators
- CBM Calculator to work out the total CBM of a shipment with several carton sizes and how many cartons fit in a container.
- Container Loading Calculator to check how pallets and cartons fit in a container.
- Trailer loading calculator for road trailers.
- Volumetric Weight Calculator to compare volumetric weight with actual weight and find the chargeable weight.
- Warehouse storage and capacity planner for how many pallets your warehouse can hold.
The results are planning estimates. Real loads depend on your cartons, pallets, vehicle and the forwarder’s instructions, and should be confirmed before you commit to a booking.