: You can also order these supplies by calling the USPS Package Supply Center at 1-800-610-8734 . 2. FedEx and UPS
While they operate differently than the USPS, they also offer fixed-rate shipping options with dedicated packaging.
: For larger quantities (packs of 10 or 25), you can order them for free at the USPS Store . They will be delivered directly to your door at no cost.
: You can get FedEx One Rate boxes for free at any FedEx Office location or by ordering them online through the FedEx website .
You don't actually have to standard flat rate boxes; for major carriers like the USPS , the boxes themselves are free as long as you pay for the corresponding shipping service. Here is where you can find them: 1. United States Postal Service (USPS) The USPS is the most common source for flat rate boxes.