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How to Save on Shipping with USPS Priority Mail Cubic Pricing

Guest Blog from Visible Supply Chain Management

The coronavirus pandemic caused a major consumer shift from in-store to online shopping, driving brick-and-mortar retailers to quickly establish an online presence—without necessarily knowing the ins and outs of ecommerce. After all, most retailers didn’t start their businesses because they wanted to be experts on shipping. That’s where partners come in. Our goal is to help both new and experienced retailers be as savvy as possible when it comes to shipping, so they can take advantage of savings and keep their businesses growing.

A lesser-known way to save is by taking advantage of USPS Priority Mail Cubic Pricing. While this isn’t a new offering from USPS, it may be new to retailers getting their feet wet in ecommerce and a bit mystifying even for longtime shippers. For this reason, we’re breaking down how Cubic Pricing works, how to qualify for these savings and how to evaluate your packaging with savings in mind.


USPS Cubic Pricing is one of the most cost-effective ways to ship small, heavy packages. While shipping rates are typically calculated based on the weight of a package, Cubic Pricing is based on the size of the package and distance traveled.


In order to qualify for Cubic Pricing, a shipper’s volume typically must exceed 50,000 packages per year. However, customers of DesktopShipper and Visible Supply Chain Management can access these discounted USPS rates without meeting the traditional shipping volume required.


Cubic Pricing is based on the dimensions of your package rather than on weight. To qualify, your packages must:


  • Weigh less than 20 pounds
  • Measure no more than .50 cubic feet (cubic feet can be calculated by using the equation length x width x height / 1,728)
  • Have no side exceeding 18”

Note: If one of the measurements exceeds the nearest quarter inch, round down to the nearest quarter inch (e.g., 8.6” rounds down to 8.5”).


Pricing is determined based on the tier the package falls under. These tiers are:

  • 1: Packages up to .10 cubic feet
  • 2: Packages more than .10 up to .20 cubic feet
  • 3: Packages more than .20 up to .30 cubic feet
  • 4: Packages more than .30 up to .40 cubic feet
  • 5: Packages more than .40 up to .50 cubic feet


Fractional results should be rounded up to the next tier (e.g., a package that is 0.24 cubic feet will be in the 0.3 tier). After you know your tier, pricing will be determined based on distance traveled.



Let’s take a look at an example. A package with dimensions of 8” x 8” x 6” and weighing 10 pounds would fall under the .3 cubic pricing tier (8 x 8 x 6 / 1,728 = .22). If the package is traveling from Salt Lake City, UT to Orlando, FL, which is more than 1,800 miles and Zone 8 pricing, the cost to ship would be $13.25.

Cubic Tier

Zone 0,1,2

Zone 3

Zone 4

Zone 5

Zone 6

Zone 7

Zone 8

Zone 9















































However, if you didn’t take advantage of Cubic Pricing and rated this package based off weight and zone rather than package size, it would cost you nearly three times that much: $39.67.

In this example, the shipper saves $26.42. When you consider your shipping volume over the course of a year, this can add up to serious savings and a have significant impact on your bottom line.

Tip: When it’s time to print your shipping label, be sure to enter your box dimensions—especially if your box is under .5 cubic feet—to ensure you get those savings.


No, Cubic Pricing isn’t just for boxes. While tubes and rolls don’t qualify, envelopes do—as long as no side is longer than 18”, the smallest dimension is under 2” and the sum of the two longest dimensions does not exceed 36”.


If a box exceeds 1 cubic foot, the shipping cost will be based on the actual weight or dimensional weight—whichever is greater. For that reason, Cubic Pricing can be looked at as an incentive to avoid large, lightweight shipments and ship heavier items in smaller packages instead. As a shipper, it’s important to evaluate your packaging options and assess whether shipping smaller, heavier packages is an option for your business.


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Through DesktopShipper and Visible Supply Chain Management, companies of all sizes have access to the leading shipping automation platform and the most cost-effective shipping options available. You won’t find Cubic Pricing at your local post office—fortunately, you can find it here. For more information about how DesktopShipper and/or Visible can support your business, contact our team today!

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