How to Use Priority Mail Flat-Rate Boxes

by Lindsey Thompson; Updated September 26, 2017

The United States Postal Service offers customers a simple way to ship packages with its Priority Mail flat rate boxes and Priority Mail Express boxes. Priority Mail flat rate boxes take one to three days to ship, depending on the destination, and they come with free online tracking and package insurance up to $50. Priority Mail Express boxes have guaranteed overnight delivery 365 days a year, as well as free tracking and insurance up to $100.

Pick Your Boxes

Several types of Priority Mail flat rate packages are available, including padded and legal envelopes and small, medium and large boxes. Priority Mail Express packages include padded and legal envelopes, as well as top-loading and side-loading boxes. The Priority Mail flat rate and Express boxes are available for free at all USPS post offices and branches. You can also order the boxes at no cost by submitting a request on the USPS website.

Prep Your Shipment

Check the list of restricted items on the USPS website. These items include hazardous materials, ammunition, gasoline and explosives. Assuming your item is not on that list, include enough packing material to keep the items safe while in transit. When you seal the box, the flaps must lie flat and close completely. Tape the box shut and do not use twine or string. Your item or items can weigh up to 70 pounds.

Print a Label

Once packed, the Priority Mail package needs a mailing label. You can purchase and print out a label through the USPS website or you can buy a label at a USPS post office counter or self-serve kiosk. Be sure to print the address legibly using a pen or permanent marker, and include the additional four zip code digits if you know them. If the package is fragile or breakable, label the box as such. If mailing to a military APO, FPO or DPO, fill out a customs form. Military packages sent in the large Priority Mail flat rate box receive a discount.

Mail Your Box

You can drop off the flat rate box at your local post office. The USPS offers a search feature on its website to find the post office closest to you. If you don’t want to leave your house, schedule a free online pickup through the USPS website and your postal carrier will pick up the box from your mailbox or front porch. You can also have them pick up the box at your business location. To set up a free pickup on the USPS website, choose a date, enter in the type of package and the weight, and indicate where you will leave the package for the mail carrier.

About the Author

Lindsey Thompson began her writing career in 2001. Her work has been published in the Cincinnati Art Museum's "Member Magazine" and "The Ohio Journalist." Thompson holds a Bachelor of Science in journalism from the Scripps School of Journalism at Ohio University.

Photo Credits

  • Tyler Grove/Demand Media