As a rule of thumb when calculating international freight rates we generally consider volumetric weight as the defining characteristic for calculating ocean freight costs as a large ocean-going freighter isn’t very sensitive to how much weight is in any one particular container.
Conversely, for cargo that rides in an airplane, weight is often the limiting factor on how much cargo an airplane can safely take off and land with. That said, there can be an exception to this rule if and when the contents of a package is so light that the space it takes up in an airplane may cost more than its cost when using weight as the only criteria. This is when the term “volumetric weight” or “chargeable weight” becomes part of the calculation.
To make this more easily understood, let’s use a rather silly example to demonstrate why sometimes “volumetric weight” is the most practical method for calculating air freight costs:
Let’s pretend that a person want to ship an entire cargo plane load of inflated balloons from one destination to another. Obviously, a plane full of balloons won’t be very heavily loaded and if we were to charge based exclusively on weight alone, this airline would soon be bankrupt charging by the pound or kilogram!
If you are going to ship a package via air freight that is rather bulky, you can calculate the cost based as follows –
- For volumetric weight in kilograms, just measure the length X width X height in centimeters and divide by 5000.
- For volumetric weight in pounds, you will measure length X width X height in inches and then divide that number by 139.
If the volumetric weight is higher than the actual weight, then use the volumetric weight or chargeable weight for the cost calculation. If the actual weight is higher than the volumetric weight, then you need to just use the actual weight and multiply that number by the cost per pound or kilogram to know what your total cost will be.