How this calculator works
CBM is a volume, found by multiplying the three carton dimensions in metres. A carton of 50 by 40 by 30 centimetres is 0.5 x 0.4 x 0.3 = 0.06 cubic metres. Multiply by the quantity for the shipment total. Carriers charge whichever is greater of the actual weight and the volumetric weight, because a light parcel can take up as much space as a heavy one. Volumetric weight divides the volume in cubic centimetres by an agreed factor: 6000 for air freight, 5000 for express couriers, and 1000 for sea freight where one cubic metre is treated as one tonne. The container count here is a pure volume estimate and ignores stacking losses, pallets and payload limits.
Formula
CBM per carton = length x width x height in metres. total CBM = CBM per carton x quantity. volumetric weight (kg) = total CBM x 1,000,000 / factor in cm³ per kg. chargeable weight = the greater of actual weight and volumetric weight. cartons per container = floor(container volume / CBM per carton).
Worked example
A 50 x 40 x 30 cm carton is 0.06 m³. One hundred cartons are 6 m³ and weigh 1,000 kg. At the air cargo factor of 6000 cm³/kg the volumetric weight is 6,000,000 / 6000 = 1,000 kg, so the chargeable weight is 1,000 kg. At the courier factor of 5000 it is 1,200 kg, so the chargeable weight rises to 1,200 kg even though the goods weigh 1,000 kg.
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Frequently asked questions
Why is my chargeable weight higher than the scale weight?
Freight is priced on the space a shipment occupies as well as its mass. When the volumetric weight is larger, the carrier charges that instead. Packing more densely, or choosing a smaller carton, brings the two figures closer together.
Which volumetric factor should I use?
Use the one in your carrier contract. Air cargo commonly uses 167 kg per cubic metre, which is the same as 6000 cm³/kg. Express couriers often use 5000 cm³/kg, and sea freight uses 1000 cm³/kg or a revenue ton. The container volumes are also approximate; check the carrier's specification.
Does a container really hold this many cartons?
No. The count here divides volumes and assumes perfect packing. Real loading loses space to pallets, door openings, corrugation and the need to brace the load. A practical planning figure is 80 to 90 percent of the pure volume count, and the weight limit can bind sooner on dense goods.
What is the difference between CBM and freight ton?
A freight ton or revenue ton is a pricing unit that takes the greater of one cubic metre and one tonne. CBM is just the volume. Sea freight quotes often show a rate per revenue ton, so a light but bulky shipment is priced on its cubic metres.