Why does the volume of a PostNL shipment to a destination outside of the EU affect the rate applied?

Since January 1, 2021, the kilogram surcharge, depending on the volume (dm3) of the shipment, is determined based on either the actual weight (in kg) or the volumetric weight. This new method was introduced to impose higher charges on shipments that take up more space and/or weight during transport compared to smaller and/or lighter shipments. This means that if the actual weight of a shipment is greater than the volumetric weight, the actual weight will be used to calculate the kilogram surcharge. If the volumetric weight is greater than the actual weight, then the volumetric weight will be used. We explain how it works exactly with the example below.

Calculation example for a shipment of 3 kg:
Size: 40 x 30 x 60 cm
Volume: 4 x 3 x 6 dm = 72 dm3
Actual weight: 3 kg
​​​​​​​Volumetric weight: 72 / 7.5 = 9.6

The volumetric weight is calculated based on the volume (dm3) / 7.5. In the situation above, 9.6 is therefore used to calculate the kilogram surcharge. The weight is rounded up to the nearest whole kilogram. A weight of 10 kg will be used to calculate the kilogram surcharge for this shipment.