

Multiply Length x Width x Height and divide by 166 to get the DIM weight in pounds.If your package is larger than 1 cubic foot (1,728 cubic inches): Dimensional (DIM) weight rates apply to large, lightweight packages.Maximum combined length and girth (girth is the distance around the thickest part) is 108 inches.You’ll need to measure your package to make sure it meets the size standards.Pay for your package based on how much it weighs and how far it’s going (the zone).Use your own box and pay by weight and zone (distance): When sealing a Flat Rate Envelope or Box, the container flaps must be able to close within the normal folds.Use our Priority Mail Flat Rate Envelopes or Boxes that come in standard sizes so you don't have to worry about measuring them.Pay the same price for mailpieces weighing up to 70 lbs going anywhere in the U.S.Each envelope is unique in size and structure and has differing use cases.Weight, Size, & Shape Requirements Use USPS Priority Mail Flat Rate packaging and pay one price: There are 5 different options for USPS Flat Rate Envelopes. That being said, let's dive into the different USPS Priority Mail Box and Envelope options. With a USPS Flat Rate Box or Envelope, you will be able to ship any item of any weight up to 70lbs to any location for the same price assuming it fits properly, without any bulging, within its designated box or envelope. If using non-customized boxes is not a deal breaker for you, USPS Flat Rate Shipping is a great tool to spend less on shipping. This can be a drawback for some because, unless you are a high volume shipper, you cannot get customized boxes with specific branding. In order to have access to the USPS Priority Mail Flat Rate pricing, you must use one of USPS designated Flat Rate Boxes you cannot use just any box of the same dimensions. You can pick them up at any post office or USPS will actually ship the boxes opens in new tab open_in_new to you for free. One of the many benefits of shipping with USPS Flat Rate Boxes is that the boxes themselves are free. How You Can Use USPS Flat Rate Boxes and Envelopes to Save on Shipping
