Priority Mail is the fastest mailing service offered by the United States Postal Service (USPS). It is commonly used by eCommerce sellers to expedite the delivery of parcels weighing up to 70 lbs or 108”. 

While you can purchase Priority Mail boxes online or at the post office, many people wonder if they can ship Priority Mail using their own. The answer is yes! You’re allowed to ship Priority Mail using your own boxes, given that they meet the size, condition, and label requirements.

However, it’s important to note that using an official Priority Mail box is compulsory when you’re shipping an envelope or a Flat Rate Box. In this article, we’ll share a simple guide to using your box when shipping Priority Mail and important details to consider. 

How to Use Your Own Boxes When Shipping Priority Mail

Below are the key steps to using your own boxes to ship parcels instead of using Priority-branded USPS boxes:

  1. Select a Box (New or Used) – The first step is to find a box that meets USPS’ size and condition requirements, detailed in the section below. You can either make your box using cardboard and tape or use any old packaging available at your disposal. 
  2. Measure Your Box to Verify – Once you’ve picked a box, you need to verify its dimensions. As per USPS, the maximum combined length and girth can be no more than 108 inches. So, make sure you use a measuring tape to measure the distance around the thickest part, so it doesn’t exceed the maximum allowable dimensions.  
  3. Pack in Goods – Once you’ve verified the box dimensions, you can start packing the goods up to the required weight limit detailed in the section below. 
  4. Seal Package – Make sure you seal the package, preferably using a tape dispenser to simplify the process. You can double-tape the openings and edges to increase security and minimize tampering. 
  5. Print Priority Shipping Label – From the USPS website, you can download and print your domestic or international “Click-N-Ship” label by entering your return and delivery address, shipping date, package details, and other information. Once you select the desired service (Priority Mail), you can review the label and make any necessary changes before saving it as a PDF file and printing it. Make sure that no old shipping labels are on the box.
  6. Drop-off Box – Finally, you can attach the label to the box and either drop it at a blue collection mailbox or any post office mail drop slot (make sure that you identify one that accepts your parcel size).

What to Take Note of When Using Your Own Boxes for Priority Mail 

When shipping a parcel using your own box, you’ll need to take note of certain aspects to ensure no disruptions or rejections in the process. For starters, you should know that by not using a Priority Mail box, you will be charged a variable price.

This means that the amount would be calculated based on the package weight. Below are other things you need to take note of:

Box Dimensions

As mentioned earlier, you should ensure your box meets USPS’ standard sizes in length and weight. Otherwise, you may have to pay additional fees. If the package size exceeds 1 cubic foot (1,728 cubic inches), dimensional weight rates will apply. 

USPS determines if the box meets the standard limit by multiplying Length x Width x Height and dividing the total by 166. If the DIM weight is more than the actual package weight, the shipper must pay the DIM weight price.

Box Condition

The second important thing to note is the box condition. If you’re using an old box, check for any damage, old labels, and markings. Also, check the box’s structural integrity to minimize the risk of tearing during transit. 

Secondly, if the box is in good condition but has labels or marks, you should consider either removing them or wrapping the box in brown paper before placing the priority mail label. The brown paper will conceal any irrelevant information that could confuse the courier.   

Non-Compliance Fees

Failure to provide accurate dimensions or paying the DIM weight rate when it applies can prompt USPS to charge a dimension non-compliance fee. In other words, you’ll be paying an extra fee for sending nonstandard-sized packages. Here’s a table showing the additional fees:

Box SizeAdditional Fee
Between 22 and 33 inches in length $4.00
More than 30 inches in length$15.00
More than 2 cubic feet in length$15.00

Drop Off Locations

Finally, you will need to drop off your consignment at the right locations. USPS offers two options – the first being blue collection mailboxes and the second being post office mail drop slots.

Blue collection mailboxes are ideal for boxes weighing 10 oz. (or less) or ½ inch in thickness (or less). Conversely, post office mail drop slots are for large boxes. To find the most convenient location for parcel drop offs, simple head over to the USPS Locator.

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Agnes Aui

Head of Marketing
at freightcourse

About the Author

Agnes is the Head of Marketing at freightcourse and seamlessly blends her strong background in content management with strategic marketing expertise.

She brings a wealth of knowledge to readers, specializing in various e-commerce topics such as order fulfillments, purchasing, payments, and more.