Package Sizes and Dimensions - USPS Domestic Overview

Shipping dimensions are only used if you are sending a shipment in a custom box or envelope rather than in a carrier's flat-rate packaging. The shipment dimensions will affect the cost of the shipment, so accurate measurements are important.

Dimensional (cubic) pricing and dimensional (DIM) weight pricing are based on volume (length x width x height) rather than physical weight as the volume determines how much space the package takes up in the truck or airplane.

Length: The longest size of the package.

Width: The distance from one side to the other on the shortest part of the package.

Height: The distance from top to bottom of a standing package.

"Machinable" packages mean they are able to be sorted by a machine. If your package is larger than the machine is able to sort, it will be bumped into the next class of letters or packages, which often costs more money.

Machinable - Oversized vs Minimum dimensions

Oversized Priority Mail packages may be subject to dimensional pricing even when below the maximum 108" dimension. 

Packages are also subject to minimum dimensions. No package may be smaller than 5" x 3.5" x 0.007". Machinable packages may not be smaller than 6" x 3" x 0.25".

Non-Machinable Surcharge Fee

Non-machinable packages may be subject to surcharge fees. Learn more about physical standards for parcels.

If you can answer “Yes” to any of the following questions, you may have a non-machinable package that will incur an additional fee.

Measuring Girth

When determining your package size, you may need to know the package's girth.

Girth: The width and height of a package doubled and added together.

Some domestic shipping supplies are offered for free through the USPS.

Click on the following options to order free boxes:

ShippingEasy offers tools to make selecting the right carrier and package even easier.