You can obtain official USPS flat rate packaging through these official channels:
: Most retail locations have a dedicated area in the lobby where you can pick up a few boxes for free. High-volume types like Medium and Large boxes are almost always in stock. where to buy flat rate boxes
: You cannot use your own box and claim the flat rate price; you must use the branded USPS Flat Rate container. You can obtain official USPS flat rate packaging
: You can call the USPS Package Supply Center at 1-800-610-8734 to request free supplies by phone. Alternative and Retail Options where to buy flat rate boxes