Dimensional Weight: How Box Size Drives Shipping Cost

Carriers often bill on whichever is greater: a parcel’s actual weight or its “dimensional weight” – a number based on its size. That means an oversized box can cost more to ship even when it is light. This guide is part of our how to measure guide.

What is dimensional weight?

Dimensional (or volumetric) weight converts a box’s volume into a billable weight. Major carriers calculate it as length x width x height divided by a divisor (commonly 139 for inches and pounds on US domestic shipments). If that number is higher than the actual weight, you are billed on it.

A simple example

A 12 x 12 x 12″ box has a volume of 1,728 cubic inches. Divided by 139, that is about 12.4 lb of dimensional weight – so even a 3 lb product in that box may be billed as ~13 lb. Shrink the box to fit and the bill drops.

How right-sizing cuts the bill

A box built to the product lowers the dimensional weight directly, and cuts void fill too. Over hundreds or thousands of orders, that adds up fast. See how to measure and mailer box sizes.

Custom sizing is the fix

Because we build boxes to your exact dimensions with no die or plate fees, right-sizing for dim weight costs nothing extra – it just saves on every shipment. See packaging cost.

Right-size your shipping boxes

Tell us your product and we will size a box to minimize dimensional weight, with a free dieline. Start with our measuring guide, then request your free quote or contact our team.