In sea groupage (LCL) the consolidator charges per “revenue ton”: it compares the weight in tonnes with the volume in cubic metres and invoices the larger figure. Under the 1 t = 1 m³ convention, a 2 m³ / 800 kg shipment pays 2 units; a 1 m³ / 1,500 kg one pays 1.5.
Local charges at origin and destination are often calculated per W/M as well, with minimums per shipment. When comparing an LCL quote with a 20’ container, add everything up: beyond a few cubic metres the full container usually wins.