How to Calculate CBM for Shipping: Formula & Examples

What is CBM?

CBM stands for Cubic Metre — the standard unit used in sea freight to measure the volume of cargo. One CBM equals a cube with sides of 1 metre (1m × 1m × 1m = 1 CBM). Understanding CBM is essential for getting accurate freight quotes, choosing between FCL and LCL, and calculating LCL costs.

The CBM Formula

CBM = Length (m) × Width (m) × Height (m)

If you measure in centimetres: CBM = L(cm) × W(cm) × H(cm) ÷ 1,000,000

If you measure in inches: CBM = L(in) × W(in) × H(in) ÷ 61,023.7

Worked Examples

Example 1: You have 50 cartons, each 60cm × 40cm × 30cm.
Volume per carton: 0.60 × 0.40 × 0.30 = 0.072 cbm
Total volume: 0.072 × 50 = 3.6 CBM

Example 2: A pallet is 120cm × 100cm × 150cm (including pallet height).
Volume: 1.20 × 1.00 × 1.50 = 1.80 CBM

Example 3: Mixed cargo — 20 cartons (60×40×40cm) + 5 pallets (120×100×120cm).
Cartons: 0.60 × 0.40 × 0.40 × 20 = 1.92 CBM
Pallets: 1.20 × 1.00 × 1.20 × 5 = 7.20 CBM
Total: 9.12 CBM

Weight-to-Volume Ratio (W/M Ratio)

In LCL shipping, freight is charged on CBM or tonne, whichever is greater (called the W/M or "weight/measure" principle). The standard ratio is 1 CBM = 1 Tonne for LCL.

If your cargo weighs 3 tonnes but occupies only 2 CBM, you pay on 3 units. If it weighs 1 tonne but occupies 4 CBM, you pay on 4 units.

Volumetric Weight for Air Freight

Air freight uses a different calculation. Volumetric (dimensional) weight = L(cm) × W(cm) × H(cm) ÷ 6000, result in kg. You pay on actual weight or volumetric weight, whichever is higher.

Example: A box measuring 60×50×40cm. Volumetric weight = 60 × 50 × 40 ÷ 6000 = 20kg. If actual weight is 5kg, you pay on 20kg.

CBM and Container Capacity

20ft container: 25–28 CBM usable capacity | 40ft standard: 55–58 CBM | 40ft High Cube: 60–67 CBM. These figures assume efficient loading. Irregular cargo shapes reduce usable capacity.

Practical Tips

• Always measure the outer dimensions of packed cartons, not product dimensions
• Include pallet dimensions and height in your calculation
• Round up to 2 decimal places when calculating
• Ask your supplier for carton measurements and quantities — do not estimate
• For irregularly shaped cargo, use the smallest enclosing rectangle

Frequently Asked Questions