Volumetric weight

The formula is length × width × height in centimeters divided by a divisor set by the mode: 6,000 for most air freight, 5,000 for express and courier services and 3,000 for European road groupage. Per cubic meter, those divisors equal about 167, 200 and 333 kg. When working in inches and pounds, US air freight commonly divides cubic inches by 166.

Volumetric weight is not what you pay: it is compared with the actual gross weight, and the higher of the two becomes the chargeable weight. Nor is it the same as volume. Cubic meters measure space; volumetric weight turns that space into kilograms so it can be priced against a per-kilogram rate. European road freight often uses loading meters for the same purpose.

Example: a carton of 60 × 40 × 40 cm weighing 8 kg has a volume of 96,000 cm³. By air that gives 96,000 ÷ 6,000 = 16 kg, and by courier 19.2 kg, so either way it is charged on volume rather than on its 8 kg. Measure at the widest points, including the pallet and any overhang, and cut empty space from the packaging where you can.