Why it Costs More to Ship a Box of Feathers than a Box of Bricks

Customers are often surprised to find out that the cost to ship a “lighter” load is often higher – sometimes much higher – than the cost to send a much heavier package.  It just seems to make sense that something that weighs next to nothing – a pillow for example – should be less expensive to ship than a box of books, or some tools.

But if you think about it, what takes up more space on a delivery truck – the pillow or the book?  A carrier would be hard pressed to turn a profit if a truck full of pillows was charged based solely on weight.

Instead, the shipping industry uses a calculation called “dimensional weight,” or “dim weight” to determine shipping costs.  Dimensional weight takes into account a shipment’s size and volume.  This allows a carrier to charge based on the actual space a package takes up on a truck, rather than on weight alone.  A carrier will determine a shipment’s dimensional weight and, if the dim weight is more than the actual weight, will use the higher figure to calculate costs.

How to minimize your dim weight assessments?  For one thing, keep your packaging as tight as possible – use a carton that closely fits the enclosed materials and avoid unused space.  You can also shop around to find out carriers’ dim weight divisors – the lower the divisor, the higher your package’s dim weight will be.  And the higher the dim weight, the higher the cost to ship.

*Most major carriers use the dimensional weight standard established by the International Air Transport Association (IATA).  Currently that standard for domestic shipments is 166, if multiplied by inches, or 6,000 if multiplied by centimeters.  However, carriers are not bound to the IATA standard and are free to use whatever dim weight divisor they wish.