How to use the CBM calculator
- Choose your units — centimetres, inches or millimetres, and kilograms or pounds.
- Enter the outer carton dimensions, the number of cartons and the gross weight per carton. Add more rows for mixed carton sizes.
- Read the total CBM, cubic feet, gross weight and chargeable weight for sea LCL, air cargo and express couriers.
- Check how full a 20ft, 40ft or 40ft High Cube container would be.
How to calculate CBM
CBM = Length (m) × Width (m) × Height (m) × Number of cartons
With centimetres, divide by 1,000,000: a carton of 60 × 40 × 50 cm is 60 × 40 × 50 ÷ 1,000,000 = 0.12 CBM. 100 of these cartons make 12 CBM. With inches, divide the cubic inches by 61,024. One CBM equals 35.315 cubic feet.
Container capacity
| Container | Internal size (approx.) | Theoretical volume | Practical loading |
|---|---|---|---|
| 20ft standard | 5.90 × 2.35 × 2.39 m | ≈ 33 CBM | ≈ 25–28 CBM |
| 40ft standard | 12.03 × 2.35 × 2.39 m | ≈ 67 CBM | ≈ 55–58 CBM |
| 40ft High Cube | 12.03 × 2.35 × 2.69 m | ≈ 76 CBM | ≈ 65–68 CBM |
Exact dimensions and maximum payloads vary by shipping line and container. Heavy goods may reach the weight limit before the container is full.
Chargeable weight explained
Freight is charged on whichever is greater: the actual weight or the “volumetric” weight based on size.
- Sea LCL (less than container load): charged per “revenue ton” — 1 CBM or 1,000 kg, whichever is greater (often written W/M).
- Air cargo: volumetric kg = L × W × H in cm ÷ 6,000 (IATA standard, equivalent to 167 kg per CBM).
- Express couriers (DHL, FedEx, UPS): usually L × W × H in cm ÷ 5,000 (200 kg per CBM).
Tips to reduce freight cost
- Ask suppliers to optimise carton sizes so they stack without gaps on standard pallets.
- For FBA, check Amazon’s carton limits (generally a maximum of 25 inches on any side and 50 lb per box unless the item itself is larger).
- Above roughly 15 CBM, a full 20ft container is often cheaper than LCL — ask your forwarder for both quotes.
Frequently asked questions
How do I calculate CBM in cm?
Multiply length × width × height in centimetres and divide by 1,000,000. Then multiply by the number of cartons.
How many CBM fit in a 20ft container?
About 33 CBM theoretically, but around 25–28 CBM in practice once you allow for gaps between cartons.
How many cubic feet are in one CBM?
One cubic meter equals 35.315 cubic feet.
What is chargeable weight?
The weight freight is billed on — the greater of actual weight and volumetric weight. For air freight, volumetric weight is usually L × W × H (cm) ÷ 6000.