CBM & Chargeable Weight Guide

1. What is CBM?

CBM stands for Cubic Metre — the standard unit for measuring cargo volume in international shipping. 1 CBM = 1m × 1m × 1m = 1,000 litres. To calculate CBM, measure your carton or pallet in metres and multiply: Length × Width × Height.

For example, a carton measuring 60cm × 50cm × 40cm = 0.6m × 0.5m × 0.4m = 0.12 CBM. If you have 50 such cartons, total volume = 6 CBM.

2. Chargeable Weight for Sea Freight

In sea freight (LCL), carriers use "freight tonne" or "revenue tonne" — whichever is higher: actual weight (in tonnes) or volume (in CBM). Since 1 CBM ≈ 1,000 kg for sea freight calculation, a shipment weighing 800 kg but occupying 1.2 CBM will be charged as 1.2 freight tonnes.

Example: 10 packages, each 0.1 CBM, total 1.0 CBM. Actual weight 600 kg. Chargeable = 1.0 freight tonne (because 1.0 > 0.6).

3. Chargeable Weight for Air Freight

Airlines use a different volumetric factor. Standard IATA formula: (Length × Width × Height in cm) ÷ 5,000 = Volumetric Weight in kg. Some couriers use 6,000. The airline charges whichever is higher: actual gross weight or volumetric weight.

Example: A box measuring 80cm × 60cm × 50cm = 240,000 cm³. ÷ 5,000 = 48 kg volumetric weight. If actual weight is 35 kg, you pay for 48 kg. If actual weight is 55 kg, you pay for 55 kg.

4. How to Reduce Chargeable Weight

• Optimise packaging: Use custom-sized boxes instead of standard sizes with empty space.
• Vacuum packing: For textiles and soft goods, vacuum compression can reduce volume by 50–70%.
• Remove unnecessary packaging: Decorative boxes and excess filler add volume without value.
• Consolidate shipments: Combining multiple small boxes into one large pallet often reduces total chargeable weight.
• Choose the right Incoterm: FOB vs EXW affects whether you control packaging decisions.

5. Common Calculation Mistakes

• Mixing units: Always convert to consistent units (metres for sea, centimetres for air) before calculating.
• Ignoring pallet dimensions: Include pallet height and overhang in your calculation.
• Forgetting irregular shapes: For cylindrical or irregular cargo, measure the smallest rectangular box that would contain it.
• Using wrong DIM factor: Confirm whether your carrier uses 5,000 or 6,000 for air freight.