How to calculate CBM for ocean freight (and when it decides your freight cost)
Ask a forwarder for a quote and the first thing they ask back is your CBM. That is because sea LCL, air, courier and road freight are all charged on the greater of actual weight and volumetric weight, and for light, bulky produce and packaging that is very often the volume, not the weight, that sets the price.
The CBM formula
CBM = length x width x height, all in metres, per package, then multiplied by how many packages you have. A carton 0.4 m by 0.3 m by 0.25 m is 0.03 CBM; 500 of them is 15 CBM.
The formula never changes. What changes by freight mode is what a cubic metre is worth in kilograms, which is what actually decides your price.
Why volume can cost more than weight
Sea LCL is billed per revenue ton: the greater of your cargo's cubic metres and its weight in tonnes, so 1 CBM competes directly with 1000 kg. Air freight uses a volumetric divisor, commonly 6000 cm3 per kg (about 167 kg per CBM); air courier uses 5000; road LTL commonly uses 3000. A pallet of empty-ish cartons can weigh little and still price like a much heavier shipment once the volumetric side wins.
This is exactly why two shipments with the same actual weight can come back with very different freight quotes: one was volume-bound, the other was weight-bound, and the difference is invisible until you run both numbers.
Getting it right before you book
Measure the packed carton, not the product inside it, since packaging adds real volume. If you ship several carton sizes, total each type separately and sum the CBM, do not average dimensions across types.
Run both actual weight and volumetric weight before you accept a quote, so you know which one the forwarder is charging you on and can sanity-check the number yourself rather than take it on faith.
Try the free CBM calculator
Calculate cubic metres and chargeable weight for sea, air, courier, road and rail in one tool.
Try it on your next pack run
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