Volumetric weight is calculated by multiplying length, width and height in centimetres and dividing by the mode’s factor: 6,000 in IATA air (equivalent to 167 kg/m³), 5,000 with express integrators. A 100 × 60 × 50 cm box is 300,000 cm³, that is 50 volumetric kg in air and 60 kg in express.
When volumetric weight exceeds gross weight, the volumetric figure is invoiced. So measure each piece at its widest points — corners, handles, protrusions — and cut empty packaging: every centimetre of air is paid for as if it were cargo.