What Are the USPS Boxes For? (All You Need to Know)

When visiting your local Post Office, you might not immediately notice one of the displays, which is hanging out near the front of the building, filled with boxes.

But then someone comes in and takes a box, and walks right out! What just happened? No one else seems to think anything of it. Are they free? What are the USPS boxes for in the Post Office? I’ve got the answer you need, so keep reading to learn more!

What Are the USPS Boxes for In [currentyear]?

The USPS boxes, located mostly near the front of the Post Office, are for Priority Mail and Priority Mail Flat Rate shipping, and they are completely free in [currentyear]. Customers are welcome to come in and grab as many as they need. USPS boxes can also be obtained for free via The Postal Store, USPS’s online store.

To learn more about what you can use these USPS boxes for, what the different types of boxes are, if there’s a catch with free boxes, and much, much more, keep going! I’ve got all you need to know.

What Can You Use USPS Boxes For?

The Post Office boxes (and envelopes) that are available for free are for Priority Mail and Priority Mail Flat Rate shipping only.

(Bear in mind that what is in stock at your local Post Office may vary.)

Priority Mail shipping is priced based on weight and the destination, and it includes $50 worth of insurance and Tracking.

Priority Mail Flat Rate shipping starts at just $9.45 for a small box and ranges up to $21.50 for a large. It also includes $50 of insurance, as well as Tracking.

However, note that Priority Mail and Priority Mail Flat Rate boxes can only be used for these mail classes.

In fact, it is actually illegal to try and use Priority Mail boxes for any other shipping method.

What Are the Different Types of USPS Boxes?

There are five different types of Priority Mail Flat Rate boxes, and can be found for free at Post Office locations. They are as follows:

  • Small boxes: 8-11/16″ x 5-7/16″ x 1-3/4″ 
  • Medium tall: 11-1/4″ x 8-3/4″ x 6″ Outside
  • Medium short: 14″ x 12″ x 3-1/2″ Outside
  • Large tall: 12″ x 12-1/4″ x 6″
  • Large short: 24-1/16″ x 11-7/8″ x 3-1/8″

Also, there are a variety of regular Priority Mail boxes, like tall, skinny ones such as Box 1092 or large square ones like Box #7.

Now, when you get these at the Post Office, you can take one or two (or however many you need).

However, if you’re ordering online, you will have to “purchase” them in sets of 10 or 25 in some cases.

Just as a reminder, though- you don’t actually have to purchase anything, though you will go through a check-out process.

Instead, USPS will simply verify your name and address. Then, your mail carrier will bring them with him/her on the next mail loop.

What Is the Catch With Free USPS Boxes?

What Is the Catch With Free USPS Boxes?

There’s no catch with the free USPS boxes – they are totally free, even when ordered online.

That includes shipping, too! Your mail carrier will bring them with their next mail loop and deliver them right to your front door.

This is the Postal Service’s way of encouraging people to use its shipping services.

While the USPS has a monopoly on letter mail, it competes with UPS and FedEx for package shipping.

However, if your package isn’t in a huge rush (i.e, doesn’t need to reach its destination overnight or within two days), then something like Priority Mail Flat Rate could save you hundreds.

Is It Illegal to Use Priority Mail Boxes?

It is illegal to use Priority Mail boxes for anything except Priority Mail.

That means you cannot use it for First-Class packages, Retail Ground, or any other mail class other than Priority Mail.

Further, you cannot use Priority Mail boxes for Priority Mail Flat Rate shipping, and vice versa.

The warning on every box states, “Misuse may be a violation of federal law.”

That’s because USPS is a federal agency, and you don’t want to get caught committing an act of fraud against the federal government.

Can You Return Unused USPS Boxes?

You can easily return unused USPS boxes to your local Post Office.

USPS workers will be especially glad to receive them if you’re returning boxes that are different sizes beyond the small, medium, and large sizes.

This is because USPS locations can only order a few different sizes, so having ones that are outside of the norm are a treat for the Post Office.

On this Etsy thread, one person commented, “The branch post offices here have told me many times they only get a few sizes of the Priority boxes.”

They continued, “They LOVE when I bring in extras of sizes they don’t get, or just sizes I’ve found I don’t use, and they don’t have.”

Is It Cheaper to Use Your Own Box for Priority Mail?

It will cost you the same – zero dollars – to use your own box for Priority Mail, versus one from the Post Office.

That’s because Priority Mail boxes are free through the Post Office and online.

The only time you have to pay for a box is if you can’t access the Post Office and you don’t have a box at home; then you’d have to order a box from somewhere.

To learn more, you can also see our posts on where to get USPS boxes, how to order USPS boxes, and USPS mailbox regulations.


USPS boxes, such as those found in Post Offices in the front area, are for Priority Mail and Priority Mail Flat Rate shipping, and the boxes are totally free.

The same goes for Priority Mail and Priority Mail Flat Rate boxes obtained online through The Postal Store, with the added bonus of free delivery (by your mail carrier).

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Marques Thomas

Marques Thomas graduated with a MBA in 2011. Since then, Marques has worked in the retail and consumer service industry as a manager, advisor, and marketer. Marques is also the head writer and founder of QuerySprout.com.

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