How to Calculate CBM — 3 Steps
- Enter your cargo dimensions — Length, Width, Height. Select the unit you're working in: cm, mm, m, inches, or feet. The calculator converts everything to metres automatically.
- Add quantity and optional weight per unit. For mixed cargo, click "Add Item" to create a new row for each SKU or carton type.
- Read your results. Total CBM, CFT, volumetric weight for air (÷6000) and sea (÷1000), and how many units fit in a 20GP, 40GP, and 40HC container — all shown at once, no extra steps.
What Is CBM in Shipping?
CBM stands for Cubic Metre — the standard unit of volume measurement in international freight. Every carrier, forwarder, and customs broker works in CBM. When you receive a packing list and need to quote LCL, FCL, or air freight, your first calculation is always CBM.
The formula is straightforward:
Why it matters: carriers charge based on whichever is higher — actual weight or volumetric weight. CBM is the starting point for both. Get it wrong and your quote is off before it leaves your desk. Full CBM guide →
Example: A carton measuring 50 cm × 40 cm × 30 cm = 0.5 × 0.4 × 0.3 = 0.06 CBM per carton. 100 cartons = 6 CBM total.
Container Capacity Quick Reference
| Container | Internal Volume | Max Payload |
|---|---|---|
| 20GP | 33.2 m³ | 28,000 kg |
| 40GP | 67.6 m³ | 26,500 kg |
| 40HC | 76.4 m³ | 26,330 kg |
Usable volume in practice is 85–90% of internal volume depending on cargo shape and stacking. See single container calculator for fill percentage.
Frequently Asked Questions
CBM = Length (m) × Width (m) × Height (m). Convert all dimensions to metres first, then multiply. For multiple cartons, multiply the single-unit CBM by quantity.
Example: 50 cm × 40 cm × 30 cm = 0.5 × 0.4 × 0.3 = 0.06 CBM per carton. 200 cartons = 12 CBM.
CBM is the physical volume of your cargo in cubic metres. Volumetric weight converts that volume into a weight equivalent so carriers can compare it to actual weight and bill whichever is greater.
- Sea LCL: Volumetric weight (kg) = CBM × 1,000
- Air freight: Volumetric weight (kg) = CBM × 6,000