Weight or measure (W/M)

Ocean LCL rates are quoted 'per W/M' — per weight or measure — meaning the carrier bills whichever is greater: the shipment's weight in metric tons or its volume in cubic meters, at a 1,000 kg : 1 CBM equivalence. The billed quantity is called revenue tons.

Example: 3 CBM weighing 1,200 kg bills as 3 revenue tons (volume wins); 2 CBM weighing 3,500 kg bills as 3.5 (weight wins). Light, bulky cargo therefore pays for space and dense cargo pays for mass. Air freight applies the same idea with a different ratio — 1 CBM equating to about 167 kg — which is why the mode comparison changes with density.