Free CBM calculator — cubic meters & volumetric weight

CBM stands for cubic meter — the standard unit used in international shipping to measure cargo volume. It is calculated as length × width × height, with all three measured in metres. Freight forwarders use CBM to determine how much space a shipment occupies and to calculate shipping costs, particularly for less-than-container-load (LCL) ocean freight.

Multiply the length, width, and height of your cargo in metres to get cubic meters (CBM). For example, a box measuring 0.6m × 0.4m × 0.4m has a CBM of 0.096 m³. If you have multiple identical boxes, multiply the result by the quantity. If dimensions are in centimetres, calculate in cm and divide the result by 1,000,000 to convert to cubic meters.

CBM measures pure volume in cubic meters. Volumetric weight converts that volume into an equivalent weight for billing purposes, using a carrier-specific divisor. Air freight typically uses a divisor of 6,000, while express couriers like DHL, FedEx, and UPS typically use 5,000. Carriers charge based on whichever is higher: the actual weight or the volumetric weight.

This happens when your cargo is large but lightweight — common with items like pillows, clothing, or packaging materials. Carriers charge based on space occupied, not just mass, because cargo capacity on a plane or truck is limited by volume as much as by weight. When volumetric weight exceeds actual weight, you are billed for the volumetric figure.

A standard 20ft shipping container has an internal volume of approximately 31.16 cubic meters (589cm × 230cm × 230cm). In practice, achievable fill rates are typically 70–85% due to irregular cargo shapes and loading constraints, meaning around 22–26 m³ of cargo can be packed efficiently.

A standard 40ft shipping container has an internal volume of approximately 63.48 cubic meters (1200cm × 230cm × 230cm). A 40ft High Cube container, which is 30cm taller, has approximately 71.76 cubic meters of internal volume.

Use 6,000 for international air freight and ocean freight under IATA standards. Use 5,000 for express courier services including DHL, FedEx, and UPS. Some budget or regional carriers, particularly in parts of Asia, use 4,000. Always confirm which divisor your specific carrier applies, as this can change your chargeable weight by up to 20%.

Yes — this calculator gives a volume-based estimate of how many units fit in a 20ft, 40ft, or 40ft High Cube container. This estimate does not account for stacking constraints or irregular shapes. For an accurate 3D load plan that accounts for stacking, weight distribution, and axle load compliance, Teuvia provides a free 3D load planning tool.