Can I Use USPS Boxes for UPS and FedEx Shipments?

Learn about different packaging options from the major carriers and why USPS requires you to use the proper corresponding packaging with certain services like Priority Mail
can I use USPS boxes for UPS and FedEx shipments
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On top of keeping shipping costs low by purchasing discounted postage through shipping software, packaging is another key cost for eCommerce businesses to manage. Businesses can keep packaging costs low by taking advantage of free packaging from USPS, such as Priority Mail boxes and envelopes. This is a strategy that many online businesses employ, which leads to shippers wondering whether they can use these free USPS boxes for UPS or FedEx shipments. Here are the main reasons why we don’t recommend doing this!

While UPS & FedEx Likely Won’t Stop You From Using USPS Boxes, USPS Prohibits This

Neither UPS nor FedEx will stop you from using USPS boxes for UPS or FedEx shipments. Both carriers have been known to accept shipments in boxes from other carriers, as well as shipments packaged in recycled Amazon boxes. However, we don’t recommend using USPS boxes to ship with any carrier other than USPS itself, for a number of reasons!

First off, USPS requires you to only use USPS-branded boxes (such as Priority Mail boxes) to ship with the specific USPS service marked on them. While USPS packaging is free to order and pick up at the Post Office, the Postal Service’s guidelines prevent shippers from using those boxes and envelopes to ship with other carriers like UPS and FedEx. In fact, the FAQ section of the USPS website specifically says “Misuse may be a violation of federal law.”

Secondly, injecting USPS boxes into UPS and FedEx networks may cause confusion during the sorting and distribution process.

Certain USPS Services Require You to Use the Corresponding USPS Packaging

As we said in the above section, you’ll need to follow strict packaging guidelines when shipping with USPS.

For certain services, USPS requires you to use the proper USPS-branded packaging marked with the name of that service. For instance, if you’ve purchased a shipping label for the Priority Mail Small Flat Rate box, USPS won’t accept that label unless you have affixed it to the Priority Mail Small Flat Rate box.

We’ve included a list of the USPS services that require you to use the specific corresponding packaging below:

  • Priority Mail
  • Priority Mail Express
  • Priority Mail Flat Rate
    • Flat Rate Envelope
    • Flat Rate Legal Envelope
    • Small Flat Rate Box
    • Medium Flat Rate Box
    • Large Flat Rate Box

Other USPS shipping services such as Media Mail and USPS Ground Advantage require you to provide your own packaging.

Pro Tip: If you’re in the market for free USPS boxes and/or envelopes, you can get them either at your local Post Office or you can order them online at

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  1. Claire Kern

    YOU FORGOT TO PUT PADDED FLAT RATE ENVELOPES ON THE LIST OF PACKAGING TYPES! Also, I’m not 100% sure but I think it read in one of the above descriptions that priority mail only costs a little more than ground but it is over double the cost! Also, I don’t think ground is taking much longer than before ground, not more than one day but have not tracked enough to be sure and it probably varies due to location. Also you said you are training employees for awareness about sustainability. How about training them to read addresses and pick up notices better. A very few cannot do this very well. And I sincerely hope that all of your efforts will affect the environment and also prevent continuously increasing, disturbing postage costs yearly.

  2. Sandi

    Actually it says right on the USPS packaging “Misuse may be a violation of FEDERAL Law”
    Not to be used for/with any other carrier than USPS.

  3. Michelle Williams

    Just a question: We have a ton of Regional Rate A and B boxes, and that service is no longer in use. Are we able to use those for regular USPS Priority shipping, just not selecting the obsolete “Regional A rate”? Maybe cross out the “title” on the box?

  4. Jeanne Barron

    It doesn’t matter if it’s flammable?


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