The chargeable weight for air freight is the metric on which airlines charge. It is either the gross weight or the volumetric weight, whichever is higher.

The volumetric weight for a shipment can be calculated by multiplying the height by the width by the length of the shipment in cm or meters. This will give you the cubic meter or cbm of the shipment. This amount is then divided by 0.006 and this gives you the chargeable weight of the shipment. 

For example if you have the below shipment you can see that the gross weight is 150kgs. To work out the volumetric weight you multiply 1.2 X 1.0 X 1.5 = 1.8m3. You then take the 1.8m3 ÷ 0.006 = 300kgs volumetric weight. Since the volumetric weight is higher than the gross weight, 150kgs gross compared to 300kgs volumetric weight, the higher 300kgs is the chargeable weight 

1 pallet @ 120x100x150cm – gross weight 150kgs

Another example for cartons as per the below you can see that the gross weight is 100kgs. To work out the volumetric weight you multiply 0.3 X 0.3 X 0.3 = 0.027m3 and so 0.027m3 is the cbm for 1 carton. You then multiply 0.027m3 by 10 since there are 10 cartons and this gives you 0.27m3. You then take the 0.27m3 ÷ 0.006 = 45kgs. In this case the gross weight is 100kgs and the volumetric weight is 45kgs, and so the higher 100kgs is the chargeable weight.

10 cartons @ 30x30x30cm – gross weight 100kgs