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Reviewed and updated by ICD - Week 24/2026
CBM (cubic meter, symbol m³) is a unit of cargo volume, calculated as Length × Width × Height in meters. In import-export and logistics, CBM determines freight cost, how much cargo fits in a container and how volumetric weight is converted. It is the first figure to compute when quoting freight and planning a load.
What is CBM in import-export?
CBM tells you how much space cargo takes on a vehicle (container, aircraft, truck). Carriers use CBM to charge light, bulky cargo, because for such goods volume - not weight - reflects the real space occupied. CBM applies to sea, air and road freight alike.
CBM formula
The basic formula for a rectangular package:
CBM = Length (m) × Width (m) × Height (m) × number of packages
If measured in cm, convert: CBM = (L × W × H) / 1,000,000 × quantity. Always measure the packed dimensions (including the pallet), not the bare product.
Example: 15 packages of 1.2 × 1.0 × 0.8 m → CBM = 1.2 × 1.0 × 0.8 × 15 = 14.4 CBM.
Converting CBM to kg - volumetric weight
Carriers compare actual weight (Gross Weight) with volumetric weight (converted from CBM) and charge by the greater value - the Chargeable Weight. Conversion factors by mode:
| Mode | 1 CBM equals | Note |
|---|---|---|
| Sea (LCL) | 1,000 kg | 1 m³ = 1 tonne chargeable |
| Air (IATA) | 167 kg | 1 kg = 6,000 cm³ |
| Road | ~333 kg | varies by carrier (1 kg = 3,000 cm³) |
Air example: a 14.4 CBM shipment weighing 1,000 kg has a volumetric weight of 14.4 × 167 = 2,404.8 kg. Since 2,404.8 > 1,000, it is charged at 2,404.8 kg (light bulky cargo is charged by CBM).
CBM and container capacity
Knowing a shipment’s CBM helps you pick the container type and estimate how many you need. Reference capacity:
| Container | Theoretical volume | Real load (75-85%) |
|---|---|---|
| 20ft | ~33 CBM | ~25-28 CBM |
| 40ft | ~67 CBM | ~50-57 CBM |
| 40ft high-cube (40HC) | ~76 CBM | ~58-65 CBM |
Only 75-85% of the theoretical volume is usable because of gaps between packages, cargo shape and space left for lashing. That is why on-paper CBM is always less than the nominal capacity.
CBM and choosing the right pallet
Pallet size directly affects usable CBM in a container. The 1,100 × 1,100 mm and 1,200 × 1,000 mm formats fit container floors well and minimise gaps; the wrong size leaves tens of centimetres of unused width per tier, wasting 10-15% of volume. Stacking cartons in multiples of the pallet footprint and at the right tier height maximises usable CBM. For exports, using slip sheets instead of pallets saves a whole layer of height, fitting more packages in the same CBM.
Using CBM to choose FCL or LCL
CBM also guides the sea-freight mode. Small shipments (below roughly 10-15 CBM) are usually cheaper as LCL consolidation (paid per CBM). Above that threshold, a full 20ft FCL (real capacity ~25-28 CBM) is typically cheaper per CBM and safer for the goods. Calculating CBM first lets you decide correctly from the start.
Common mistakes when calculating CBM
First, measuring the bare product instead of the boxed-and-palletised dimensions - omitting packaging understates the CBM. Second, forgetting to convert cm to m (divide by 1,000,000), causing huge errors. Third, looking only at actual weight and ignoring volumetric weight, then being surprised when the carrier charges by CBM. Fourth, not adding the pallet’s height and weight to the shipment.
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Frequently asked questions
How many kg is 1 CBM?
It depends on the mode: 1,000 kg by sea, 167 kg by air, about 333 kg by road. This is a conversion for charging freight, not the actual weight.
How many CBM fit in a 40ft container?
About 67 CBM theoretically (76 for a 40HC), but only 75-85% is usable in practice, roughly 50-65 CBM depending on cargo shape.
How do I calculate CBM from centimeters?
Multiply L × W × H in cm, divide by 1,000,000, then multiply by the quantity. For example 120 × 100 × 80 cm = 0.96 CBM per package.
What is chargeable weight?
It is the greater of the actual weight and the volumetric weight converted from CBM. Carriers always charge by the larger value.
When should I ship FCL instead of LCL?
When volume exceeds about 10-15 CBM, a full 20ft FCL is usually cheaper per CBM and safer than LCL consolidation.
Why is calculated CBM less than container capacity?
Because only 75-85% of the theoretical volume is usable, due to gaps, package shape and space left for lashing.
Contact ICD Vietnam
ICD Vietnam Industrial Manufacturing Co., Ltd - pallets, plastic crates, stretch film, forklifts and packaging solutions.
Hotline: 0983 797 186 / 090 345 9186
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