You won’t be able to ship regularly Priority Mail, Priority Mail Express, or Parcel Select Ground in that box. For example, if you have a Priority Mail Medium Flat Rate Box, that’s the service you need to pay for. In the majority of cases, USPS is very strict about paying for the exact shipping service that’s marked on your box or envelope. You Need to Pay for Flat Rate Postage If You Want to Use Flat Rate Boxes (Most of the Time) Where Can I Get Flat Rate Boxes or Envelopes?įirst thing’s first: if you’re in the market for some USPS flat rate boxes or envelopes, you can pick them up for free at your local Post Office. You can also order them on the Postal Service’s website, if you don’t feel like making the trek (hey, we don’t blame you). What If My Post Office Doesn’t Accept My Package?.

It’s Perfectly Fine to Change Flat Rate Packaging to Ship Weight-Based Priority Mail.

You Need to Pay for Flat Rate Postage If You Want to Use Flat Rate Boxes (Most of the Time).

Where Can I Get Flat Rate Boxes or Envelopes?.

However, did you know that USPS lets you alter their Priority Mail Flat Rate packaging to ship weight-based Priority Mail? It’s one of the Postal Service’s best-kept secrets that not too many everyday shippers know about…but it’s a real thing, and we’re here to tell you more about it! Table of Contents

The free boxes and envelopes on the USPS website are quite popular with shippers looking to keep packaging costs low.

Usps large priority flat rate box