Priority Mail Medium Flat Rate Box 1 – 11.125 x 8.75 x 5.75″.Priority Mail Small Flat Rate Box – 8.688 x 5.438 x 1.688″.Dual-Use Priority Mail/Priority Mail Express Medium Tube 1098 – 38 x 6.25 x 5″.Dual-Use Priority Mail/Priority Mail Express Small Tube 1098S – 25.75 x 5.25 x 5.25″.The Actual Outer Dimensions of Each Free USPS Box

In this case, we suggest entering the actual dimensions of the box, and not the listed dimensions. When you use shipping software to buy postage, you’ll likely need to enter the dimensions of your USPS boxes, if it’s not marked with a specific service such as Flat Rate or Regional Rate. In our experience, we’ve found that the dimensions USPS lists on some of these boxes are slightly different than how they actually measure up. The actual dimensions are the measurements that we physically took of each of these boxes. Heads up: all of these boxes are free to order, and USPS will deliver them right to your front door! What Do You Mean by “Actual” and “Listed” Dimensions?

We’ve published the actual as well as listed outer dimensions of all of the free USPS boxes below, along with links to where you can order them on the USPS website. Need to figure out the dimensions of your USPS box? We’ve got you covered.

Sizes of usps flat rate boxes