TNT Australia has specific guidelines regarding the dimensions and weight of the parcel it accepts. For express parcels, your parcels should not be more than 1.2x1.2x1.5m, while it is 2.4x1.2x1.8 for standard shipments. If your parcel weighs under 23 kgs, it is considered a standard parcel. But anything about that will be classified as heavy shipment, and the shipping cost will be calculated accordingly.