Package Sizes and Dimensions - USPS Domestic Overview

Additional Information from USPS

ShippingEasy wants to help you learn about the e-commerce industry. This article describes service requirements set by the United States Postal Service (USPS).

The USPS is a separate organization from ShippingEasy. For more information about USPS services, visit your local Post Office or go to

Understanding the specific package sizes and dimensions for USPS services will help you make more informed decisions about how to ship your products. This guide outlines the requirements of girth, packaging, and dimensions for domestic services.

Dimensions and Girth

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.

A shipping box is displayed with labels showing the length, width and height. Arrows around the box demonstrate girth.

"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.

  • Is the package a strange shape?

  • Does this package have improper postage or is the shipping address in a hard-to-see location?

  • Is the package in an odd container?

  • Can anything on my package get caught or tangled with other things?

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.

A shipping box is displayed with arrows indicating the girth. The formula for girth is also shown: girth = (2 times width) plus (2 times height)

Carrier Packaging

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

Click on the following options to order free boxes:

ShippingEasy Tools for Managing Packages

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

Custom Packages

If you have your own unique packaging that you use to ship your products, you can save your package size and dimension on ShippingEasy's PACKAGE SETUP page. These are for packages that are different from the normal USPS Carrier Packages. Learn more about custom packages.

Shipping Presets

Shipping Presets are saved carrier package and service types available for quick use on the ORDERS and BATCHES pages. ShippingEasy has 13 pre-loaded shipping presets available for use with USPS. You can also set your own. Learn more about shipping presets.

Carrier packages are available when using a compatible USPS service on the ORDERS page. Learn more about selecting a carrier and package in ShippingEasy.

USPS Domestic - Standard Package Sizes and Dimensions

The following tables outline the maximum weights and dimensions for domestic package and envelope types offered through the USPS.

Domestic Package Size Chart

Package Type


Max Weight

Max Dimensions


Ground Advantage (formerly First-Class Package Service)

15.9 oz

22" x 18" x 15"

Ground Advantage (Parcel Select Ground)

70 lb

Length + Girth < 130"

Priority Mail

70 lb

Priority Mail Express

70 lb

Length + Girth < 108"

Flat Rate Small Box

Priority Mail

70 lb

8-5/8"(W) x 5-3/8"(L) x 1-5/8" (H)

Flat Rate Medium Box

Priority Mail

70 lb

(Top loading) Box 1= 11" (L) x 8-1/2"(W) x 5-1/2"(H)

(Side loading) Box 2= 11-7/8"(L) x 3-3/8"(W) x 13-5/8"(H)

Flat Rate Large Box

Priority Mail

70 lb

12-1/4" (L) x 12" (W) x 6" (H)

Domestic Envelope Size Chart

Envelope Type


Max Weight

Max Dimensions


First Class Mail

3.5 oz

11-1/2" x 1/4" x 6-1/8"

Flat Rate Envelope

Priority Mail

Priority Mail Express

70 lbs

12-1/2" x 9-1/2"

Flat Rate Padded Envelope

Priority Mail

Priority Mail Express

70 lbs

11-5/8” x 15”

Flat Rate Legal Envelope

Priority Mail

Priority Mail Express

70 lbs

15" x 9-1/2"


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