How To Calculate & Use Dimensional Weight For Shipping [Video]

This post has been updated as of January 2020.

As an ecommerce or brick and mortar store, you know shipping your products is not always a dream. It’s not as simple as dropping your packages off at your local FedEx or UPS store. You have to think about shipping costs. And one of the factors that go into shipping costs is dimensional weight. If you’re worried about dimensional weight, don’t be, because here’s a huge secret: it doesn’t always matter.

We’re breaking down what dimensional weight is, why it’s important and why it doesn’t always matter to your business.

We’re even going to teach you how to score custom boxes—which can help increase your business revenue—and still end up paying less in price per package and shipping costs.

What is Dimensional Weight?

At its core, dimensional weight is a pricing technique freight carriers use to maximize shipping efficiency.

Think about dimensional weight like this: the more room you take up on a shipping truck, the more money you may have to pay. Dimensional weight calculates how much volume a box holds, and puts that volume into weight.

So don’t ship your homemade candles in an extra-large shipping box because you’ll end up paying more for the air and space you’re taking up on the truck.

Here’s a more formal definition of dimensional weight.

Before dimensional weight was implemented, shipping carriers only charged based on the actual weight of a package. This was a problem. People were packing lightweight items in large boxes. So when shipping carriers packed their shipping transportation units, they found they were packing several lightweight boxes that took up a lot of space. Since they could only pack as much based on space, they weren’t able to ship as many items at once.

Large shipping carriers like FedEx and UPS came up with a system to ship more efficiently. They chose two major factors to measure: package dimension (or volume) and actual package weight.

Dimensional weight calculates how much volume a box holds and puts that volume into weight. If the dimensional weight of the package is higher than the contents’ actual weight, you can be charged the dimensional weight costs. Whichever number is higher is what shipping carriers call your billable weight. This solved the issue of lightweight but large packages taking up space on shipping transportation units.

How to Calculate Dimensional Weight

Let’s take a page out of a middle school math class. To calculate dimensional weight, you have to first measure the volume of your shipping box. Find the sides of your shipping box and round them to the nearest whole inch. Then, take those numbers (the length, width and height) and multiply them together. This number is your box’s volume in cubic inches.

After you calculate the volume, you’ll take that number and divide it by a number called the dimensional factor, or DIM factor. This final number is your dimensional weight. You’ll then compare the dimensional weight to the actual weight of your box contents to get your billable weight.

For example, our Large Shipping Box (15” x 12” x 10”) would be 1,800 cubic inches.

You would then divide the cubic size by a dimensional factor to find your dimensional weight.

The dimensional factor is simply a number that shipping carriers use to calculate dim weight. Don't worry, we'll list the dimensional factors from major shipping companies at the bottom of this post.

Be careful when looking at dimensional factors because different shipping companies utilize different numbers.

You’ll want to find the dimensional factor by checking your shipping carrier’s website.

Dimensional Weight Formula

Here’s a formula to calculate dimensional weight:

(L x W x H)/Dimensional Factor = Dimensional Weight

How Can I Get Custom Boxes But Still Pay Less Overall?

Hear us out: it’s possible to win on dimensional weight and get custom boxes. And it’s not even as complicated as it seems. Let’s break it down.

Our team offers the lowest prices on custom shipping boxes (no, seriously, have you seen our prices?) compared to major competitors. This is thanks to our parent company, Pratt Industries. Pratt takes care of the entire recycling process. Our team passes on these savings to you, our customer, to shop incredibly affordable custom boxes.

Let’s go back to our Large Shipping Box to use as an example to show you how you can almost always ship your products in one of our custom boxes for less money than a different box size. You can compare this box to a standard 18 x 12 x 6 box.

Here’s your dimensional weight equation for our large box:

15 x 12 x 10 = 1,500

1,500/139 (FedEx dimensional factor) = 13 lbs

Here’s your dimensional weight equation for a standard 18 x 12 x 6:

18 x 12 x 6 = 1,286

1,286/139 (FedEx dimensional factor) = 9.6 lbs

Let’s say the weight of the contents inside the Brandable Box large box is 27 pounds, making that the actual weight.

And in the standard 18 x 12 x 6 you’re shipping a 25 pound product, making that the actual weight. What would be cheaper to ship? Likely the 18 x 12 x 6.

Once you’ve calculated dimensional weight, round to the nearest pound. Compare the actual weight to the now determined dimensional weight. The larger weight of the two will be the one used for billing. Need an example? Don’t stress, we’ve got you covered.

Here's the Example

You purchase a Large Shipping Box from Brandable Box. You plan to ship teddy bears to your customer through FedEx (remember, your dimensional factor will be 139). The weight of your package is 10lbs.

Box: Large Shipping Box

Length: 15 in.

Width: 12 in.

Height: 10 in.

Volume: 1,800 cubic in.

Actual Weight: 10 lbs.

Dimensional Weight: 13 lbs. (round up from 12.9 lbs.)

Because the dimensional weight is greater than the actual weight, the package will be billed as a 13 pound package versus the actual weight of 10 pounds. This causes you to pay more for a package than you would have if you picked a box size that had similar billable weights.

So let’s look at overall pricing costs.
*Please note that pricing below is an estimate and is subject to change

Large box pricing:

  • Price per box: $0.94
  • Shipping cost per box: $0.94
  • Total price of package: $14.23

That standard 18 x 12 x 6 pricing:

  • Price per box: $4.36
  • Shipping costs: $7.36
  • Total price of package: $16.84

So you see, even if you went with the standard 18 x 12 x 6 box, you'd spend more overall for your boxes. Any savings you get from dimensional weight differences will go towards that markup on your boxes. And, you won't even get your logo on it.

How Can I Get Custom Boxes But Still Pay Less Overall?

You want your box customized with your company logo. This is where Brandable Box helps you win on customization and dimensional weight. Our 15 x 12 x 10 box is priced at $0.94 per box and includes your logo on it. For free.

This makes your custom box from Brandable cheaper than that standard large box. The best part? You can potentially boost your brand loyalty and revenue. Research says 40% of shoppers will purchase again from brands with premium packaging.

While we only offer a few in-stock sizes, those sizes can help you save a lot of money on shipping and help boost your brand with a simple logo addition for no extra cost. In fact, nine times out of ten our boxes will help you save money on price per package and shipping costs. Trust us, it’s worth looking into our custom boxes.

Dimensional Factors

Finding dimensional factors can be frustrating, so we’ve pulled the numbers for you. These numbers have been updated as of January 2020.


Dimensional factor: 139


Dimensional factor: 139


A dimensional weight assessment would only apply if length x width x height is more than or equal to a cubic foot. A cubic foot is 1,728 cubic inches or 12x12x12. As of June 23, 2019, USPS announced that dimensional weight assessments will affect all shipping zones versus a select few.

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