Contrary to what many believe, FedEx and UPS charge for shipments based on billable weight, not necessarily the actual weight of the shipment.

Billable weight is defined as the weight in pounds (in the US) or kilograms (ex-US) used to assess the fees charged by the carriers for a given shipment.

The billable weight calculation is not as straightforward as it may seem. Many new Rush Order employees and most Rush Order clients are surprised to learn how these two carriers calculate the weight of each shipment.  

Billable weight is the greater of A) the actual weight of the shipment, as measured by a scale and B) the dimensional weight.

The actual weight is very straightforward. The box is weighed on a scale and the resulting weight is recorded. 

Dimensional weight (aka “dim weight”) is based on the following formula. But, be careful, Rush Order’s dimensional weight calculations with shipping carriers are significantly different. Please read on for more detail. 

The published retail dimensional weight calculation is based on the three dimensions of the box (in inches in the US) multiplied together and divided by an arbitrary value. Specifically, the publicly advertised formula is the box Length (in.) x Width (in.) x Height (in.) / 139. 

For example, a box measuring 12 inches by 10 inches by 8 inches would equate to a Dim weight of 6.9 pounds, which is always rounded up. So, the Dim weight is 7 pounds. Let’s assume the box actually weighs 5 pounds on a scale. This shipment will be billed as a 7 pound shipment, NOT as a 5 pound shipment.

Why do shipping carriers use dimensional weight? It’s simple. They do not want you shipping small items in significantly larger boxes, thus taking up valuable space in their trucks and airplanes while in transit. Larger boxes can also be difficult to handle or take up more space in regional sorting facilities.

Generally, the dimensional weight divisor or “dim factor” is a negotiable value. For example, maybe you can negotiate a dim factor of 200 or even higher for your domestic ground shipments. Maybe you can negotiate a better value for expedited and international shipments as well. This is again another reason why companies hire 3PLs, which generally aggregate larger shipping volumes to obtain better rates and better dim factors.

Negotiating a larger dim factor can yield significant savings, or avoid significant costs, depending on how you look at it.

If you need a little more help or would simply like to double check your calculations, download the billable weight calculator below. Use this Excel file to plug in the actual weight and dimensions of any shipment to assess the billable weight. Just remember to adjust the dim weight factor based on the reality of whatever you or your 3PL have negotiated with FedEx or UPS.