CBM meaning and how to calculate it
CBM means cubic metre, the unit of volume used in shipping. It is length × width × height in metres, multiplied by the number of cartons. A 50 × 40 × 30 cm carton is 0.5 × 0.4 × 0.3 = 0.06 m³, so 120 of them are 7.2 m³.
What CBM means
CBM stands for cubic metre, the unit forwarders, shipping lines and warehouses use to describe how much space a shipment takes. One cubic metre is a cube 1 m long, 1 m wide and 1 m high. A quote for sea freight, a container booking or a warehouse storage fee usually starts from the CBM of the goods.
The formula
Measure the outside of one packed carton, convert to metres, multiply, then multiply by the number of cartons:
CBM = length (m) × width (m) × height (m) × number of cartons
Dimensions are usually written in centimetres, so divide each one by 100 first. If you prefer to keep centimetres, multiply them and divide by 1,000,000 (because 100 × 100 × 100 cm³ = 1 m³).
Example: one carton size
| Step | Working | Result |
|---|---|---|
| Carton size | 50 × 40 × 30 cm | 0.50 × 0.40 × 0.30 m |
| CBM per carton | 0.50 × 0.40 × 0.30 | 0.06 m³ |
| 120 cartons | 0.06 × 120 | 7.2 m³ |
| In cubic feet | 7.2 × 35.3147 | 254.3 ft³ |
CBM for a mixed shipment
Most export orders contain more than one carton size. Work out the CBM of each line, then add them up. The weight is added the same way.
| Carton (cm) | Qty | CBM per carton | Line CBM | Line weight |
|---|---|---|---|---|
| 60 × 40 × 40 | 50 | 0.096 | 4.8 | 900 kg |
| 40 × 30 × 20 | 120 | 0.024 | 2.88 | 1,080 kg |
| 80 × 60 × 50 | 10 | 0.24 | 2.4 | 300 kg |
| Total | 180 | 10.08 m³ | 2,280 kg |
How CBM relates to container size
Container capacity is often quoted in cubic metres. These are the typical internal dimensions of standard dry containers and the volume they give:
| Container | Inside L × W × H (mm) | Volume (m³) | Typical payload (kg) |
|---|---|---|---|
| 20GP | 5,898 × 2,352 × 2,393 | 33.2 | 28,000 |
| 40GP | 12,032 × 2,352 × 2,393 | 67.7 | 26,700 |
| 40HQ | 12,032 × 2,352 × 2,698 | 76.4 | 26,500 |
| 45HQ | 13,556 × 2,352 × 2,698 | 86 | 25,600 |
The 10.08 m³ shipment above would use about 30 % of a 20GP's theoretical volume. In practice you cannot fill every gap: cartons rarely divide the inside dimensions exactly, and pallets, door clearance and securing all take space. Planning for roughly 80–90 % of the theoretical volume is a common rule of thumb, and the container loading calculator shows the real fit for a given carton size.
CBM and freight charges
Sea LCL: weight or measure
Less-than-container-load (LCL) sea freight is usually charged per revenue ton: the larger of the volume in cubic metres and the weight in metric tons. The mixed shipment is 10.08 m³ and 2.28 t, so it is charged as 10.08 revenue tons.
Air freight: volumetric weight
Airlines compare actual weight with a volumetric weight, commonly at 1:6000 (166.67 kg per m³). The same 10.08 m³ would count as 1,680 kg by volume against 2,280 kg actual, so it would be charged on the actual weight. Read more in air freight chargeable weight.
Common mistakes
- Measuring the product instead of the packed carton. Use the outside of the shipping carton, including bulges.
- Mixing units: one dimension in millimetres and two in centimetres gives a figure 10 times too large or small.
- Rounding each carton's CBM to one decimal before multiplying by hundreds of cartons. Keep three decimals per carton.
- Forgetting pallets. A palletised shipment's CBM is the pallet footprint × the loaded height, not the sum of the cartons.
Tools used in this guide
Related guides
Common questions
What is CBM in shipping?
CBM stands for cubic metre (m³). Forwarders, shipping lines and warehouses use it to measure how much space cargo takes, to choose a container and to price LCL sea freight.
How do I calculate CBM in centimetres?
Multiply length × width × height in centimetres and divide by 1,000,000. For example 50 × 40 × 30 = 60,000 cm³ = 0.06 m³.
How many cubic feet are in one CBM?
One cubic metre is 35.3147 cubic feet.
How many CBM fit in a 20 ft container?
A standard 20GP has about 33.2 m³ of internal volume. Real cargo usually fits around 80–90 % of that, depending on the carton size.
How is LCL freight charged?
Usually per revenue ton: the larger of the cubic metres and the metric tons of the shipment, with a minimum charge set by the forwarder.