RT stands for Revenue Ton, a common billing unit in international LCL (Less than Container Load) shipping.
The calculation is based on:
1 RT = 1 CBM (cubic meter) or 1,000 KG (gross weight), whichever is greater.
Example:
Shipment with 2.5 CBM, 500 KG → Charged as 2.5 RT (volume larger).
Shipment with 1 CBM, 1,500 KG → Charged as 1.5 RT (weight larger).