USPS came up with the idea to offer these particular boxes for free, along with a simple pricing structure to make shipping seem more approachable – they noticed shippers were having a hard time choosing the right USPS mail class.

Good question! To speak frankly, it’s essentially a marketing ploy (isn’t everything?). Why are Medium and Large Flat Rate Boxes Free? Why Should I Use Custom-Branded Packaging Instead of USPS Flat Rate Packaging?.Why are Medium and Large Flat Rate Boxes Free?.Like the old saying goes: “You get what you pay for.” In this case, springing for custom-branded packaging instead of free USPS boxes pays off handsomely. Even though USPS offers these boxes for free when shipping Priority Mail Flat Rate, they can still end up being almost $10 more expensive than using your own box! Simply put, using custom-branded packaging saves you money AND creates positive unboxing experiences for your customers at the same time. This is especially true in the case of USPS Priority Mail Medium and Large Flat Rate Boxes. However, sometimes the free option isn’t the best option. If you’re a normal human being, your ears probably perk up when you hear the word “free.” We’ll admit it…ours do, too.

Usps flat rate medium box dimensions