Package Sizes and Dimensions: USPS Domestic

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Below are the maximum dimensions for domestic package and envelope types as well as weight limitations for shipments and packing materials offered through the USPS.

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 packages may be subject to additional handling fees. Learn more about physical standards for parcels.

To see which of these domestic shipping supplies are offered for free through the USPS, click here.    


Package Type 


Max Weight

Max Dimensions

Package First Class Package Service 15.9 oz 22" x 18" x 15"
Parcel Select Ground 70 lbs Length + Girth* < 130"
Priority Mail** 70 lbs Length + Girth* < 108"
Priority Mail Express 70 lbs Length + Girth* < 108"
Flat Rate Small Box Priority Mail 70 lbs  8-5/8" x 5-3/8" x 1-5/8"  
Flat Rate Medium Box Priority Mail 70 lbs  13-5/8" x 11-7/8" x 3-3/8"  
Flat Rate Large Box Priority Mail 70 lbs  12" x 12" x 5-1/2" 
Large Board Game Box  Priority Mail 70 lbs  23-11/16" x 11-3/4" x 3" 
Regional Rate Box A Priority Mail 15 lbs 10-15/16" x 2-3/8" x 12-13/16"
10" x 7" x 4-3/4" 
Regional Rate Box B Priority Mail 20 lbs 14-3/8" x 2-7/8" x 15-7/8"
12" x 10-1/4" x 5" 
*Girth is a special dimensional measurement, equal to (2 x width) + (2 x height). Learn more about shipment dimensions.
**Balloon or dimensional pricing may apply to oversized Priority Mail packages even when below the maximum 108" dimension. Learn more.


Envelope Type


Max Weight

Max Dimensions

Letter 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 12-1/2" x 9-1/2"
Flat Rate Legal Envelope Priority Mail
Priority Mail Express
70 lbs 15" x 9-1/2"
Flat Rate Small Envelope  Priority Mail 70 lbs 6" x 10"
Flat Rate Gift Card Envelope  Priority Mail 70 lbs  10" x 7"
Flat Rate Window Envelope  Priority Mail 70 lbs  5 x 10"


Related articles: 

Package Sizes and Dimensions: USPS International
What is the most cost effective way to ship my packages via USPS?
What is a USPS SCAN form and why is it useful?
ShippingEasy's USPS Rate Tables 

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