Dimensional Weight

What is Dimensional Weight

Dimensional weight (also known as dim weight) is a measuring method in which the total size of your parcel is measured against the total weight.

Your package could be big but also light or small but also heavy. Since bigger packages take up more space in a vehicle, aircraft, or vessel they limit the total number of packages that can be shipped through that transportation method. To make up for that, carriers will charge more for larger packages.

This means when you are packaging your product, you will want to choose a box that is as close to the size of the order as possible while also leaving just enough space for protective infill.

If you ship a small lightweight item in a large box you could be charged more for it whereas if you ship a heavy item in a smaller box you could end up being charged less for it. Dimensional weight can hurt or help you depending on if you measure and calculate correctly.

How to Calculate Dimensional Weight

In order to calculate the dimensional weight of your package, there are four simple steps to take.

• Step 1.) Measure the length, width, and height of the outside of your package. For each of those numbers round to the nearest whole number. For example, if one side measures between 1.00-1.49 inches you would round down to 1 whereas if that side measured at 1.50-2 you would count that side as two. Note: If your box has a bulge, include that in your measurement as well.
• Step 2.) Multiply these numbers together. That will give you the cubic size of the package. For example, if your package measures 5 inches by 7 inches by 7 inches then the cubic size of your package would be 245 cubic inches.
• Step 3.) Divide the number of cubic inches by the carrier’s dimensional factor, also known as the DIM divisor. The number obtained from that calculation will be the cubic inches per pound.

UPS Dimensional Weight

When trying to determine the UPS dimensional weight of your package, you’d need to follow the steps above and divide by 139 if you measured in inches or divide by 5000 if you measured in centimeters. The equation for measuring in inches would be LxWxH/139 and the equation for measuring in centimeters would be LxWxH/5000.

FedEx Dimensional Weight

Calculating the FedEx dimensional weight of your package will be similar to UPS. You’ll need to measure the length, width, and height of your package in inches. Take those numbers and multiply them. Then divide that number by 139.

USPS Dimensional Weight

USPS dimensional weight is treated slightly differently from the other two major national carriers. You’d start by multiplying the length, width, and height of your package. If the result of that is greater than 1,728 then dimensional weight pricing would be applied.

You’d then use the equation LxWxH/139. USPS changed this divisor from 166 to 139 on July 12, 2026. The result would then be your dimensional weight and if that number is greater than the actual weight of the product, you’d be charged for that instead.

However, if when you multiply the length, width, and height and the result is less than 1,728, that means your package is under 1 cubic foot which means dimensional weight pricing is not applied. In fact, you may be able to obtain cubic pricing instead.

To check, divide your package’s cubic inches by 1,728. If the result is 0.5 or less, the package can qualify for Priority Mail Cubic pricing. USPS Ground Advantage Cubic goes up to 1 cubic foot. Both require a package that weighs 20 lb or less, with no side longer than 22 inches. Shippo shows Cubic rates automatically when your package qualifies.

Learn more about USPS Cubic pricing.

How Do Carriers Charge For Dimensional Weight

After taking the dimensional weight of your package, they will compare that to the actual weight of the package. Whichever weight is greater is the number they use when calculating shipping costs.

By choosing proper packaging, you can help limit your shipping costs while also helping the environment by wasting less material and helping to lower fuel emissions by the carriers.