To calculate CBM (cubic metres), multiply length × width × height of one carton in metres, then multiply by the number of cartons. If you measure in centimetres, multiply the three sides and divide by 1,000,000. A carton of 60 × 40 × 50 cm is 0.12 CBM, so 100 of them are 12 CBM.
Try it with your own cartons: use the free CBM calculator.
Key facts
- Formula: L × W × H (metres) × number of cartons = CBM.
- From centimetres: L × W × H (cm) ÷ 1,000,000.
- From inches: L × W × H (in) ÷ 61,024.
- 1 CBM = about 35.3 cubic feet.
- LCL is charged per CBM or per 1,000 kg, whichever is greater.
How do I calculate CBM step by step?
- Measure the outside of one carton: length, width and height. Round up to the nearest centimetre.
- Convert to metres (divide each side by 100), or keep centimetres and divide the result by 1,000,000.
- Multiply length × width × height to get the CBM of one carton.
- Multiply by the number of cartons.
- If the cartons are on pallets, measure the whole pallet instead, including the pallet base.
Example in centimetres: 60 × 40 × 50 = 120,000 cm³. 120,000 ÷ 1,000,000 = 0.12 CBM. 0.12 × 100 cartons = 12 CBM.
Example in inches: 24 × 16 × 20 = 7,680 in³. 7,680 ÷ 61,024 = 0.126 CBM. 0.126 × 100 cartons = 12.6 CBM.
If you have cartons of different sizes, calculate each size separately and add them up. Your supplier’s packing list usually shows the total CBM. Check it, because forwarders measure the cargo and bill you on what they find.
How does CBM affect my freight cost?
For LCL sea freight you pay per revenue ton: 1 CBM or 1,000 kg, whichever is greater. So 3 CBM weighing 800 kg is charged as 3, but 3 CBM weighing 4,500 kg is charged as 4.5.
For air freight, volume is converted to weight instead. See how air freight chargeable weight is calculated.
How many CBM fit in a container?
| Container | Internal volume | Realistic loadable volume |
|---|---|---|
| 20ft standard | about 33 CBM | 25–28 CBM |
| 40ft standard | about 67 CBM | 55–60 CBM |
| 40ft high cube | about 76 CBM | 65–70 CBM |
You never fill 100%. Carton sizes, pallets and stacking limits leave gaps. If your total is above about 13–15 CBM, compare LCL with a full container. See FCL vs LCL.
How many cartons fit in a 20ft container?
Divide the loadable volume by the CBM of one carton. With 0.12 CBM cartons: 26 ÷ 0.12 = about 216 cartons. Treat this as a starting estimate. Weight limits and carton strength can reduce it, so ask your forwarder or supplier for a load plan on large orders.
What to do next
- Get the carton size, gross weight and carton count from your supplier’s packing list.
- Calculate the CBM yourself and compare it with the supplier’s figure.
- Add pallet height and base if the goods will be palletised.
- Use the total to compare LCL and FCL quotes.
- Ask the supplier if a smaller carton or better packing can cut the volume.
Common mistakes
- Measuring the product instead of the outer carton
- Forgetting the pallet, which can add 10–20% to the volume
- Mixing centimetres and inches in one calculation
- Rounding down. Forwarders round up, so you should too
Related questions
- FCL vs LCL: which is cheaper for my shipment?
- How is air freight chargeable weight calculated?
- How long does shipping from China take?
Sources: Container volumes from carrier specifications (Maersk container types and sizes). Last reviewed October 2026.