Freight & Shipping
How to Calculate CBM for Shipping
CBM — cubic metres — is the volume measurement that drives most freight pricing. Whether your cargo is charged on weight or volume, you can’t get an accurate quote without it. Here’s how to calculate CBM, with a worked example.
What CBM is and why it matters
CBM stands for cubic metre — the amount of space your cargo occupies. Carriers price freight on whichever is greater, the actual weight or the volume, so knowing your CBM is essential to understanding what you’ll pay. For groupage (LCL) sea freight especially, volume usually decides the cost.
The CBM formula
The calculation is simple: length × width × height, all in metres. A carton measuring 1.2m × 0.8m × 1.0m is 0.96 CBM. For multiple identical cartons, multiply by the number of pieces. Always measure the largest points of the package, including any pallet.
Worked example
CBM on a 10-carton shipment
Each carton: 1.2m × 0.8m × 1.0m = 0.96 CBM
• 10 cartons × 0.96 = 9.6 CBM total
• At 1 CBM = 1000 kg, that’s a volumetric basis of 9 600 kg
• Charged on whichever is higher — actual weight or volume
Under ~15 CBM, LCL groupage usually beats a full container.
Working out total shipment CBM
Add up the CBM of every carton or pallet in the consignment to get the total. If your packages are different sizes, calculate each one and sum them. This total is what carriers use to quote LCL sea freight and to decide whether your cargo fits a particular container.
CBM, weight and the chargeable basis
For LCL sea freight the rule of thumb is 1 CBM = 1000 kg: the carrier charges on whichever is higher, your volume in CBM or your weight in tonnes. Light, bulky cargo is charged on volume; dense, heavy cargo on weight. Air freight uses a different volumetric rule, which we cover separately.
How CBM affects your shipping choice
Your total CBM tells you whether LCL (sharing a container) or FCL (a full container) is more economical, and which container size you need. As a rough guide, once you’re past roughly 15 CBM, a full 20ft container often works out cheaper than groupage.
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