USPS Package Restrictions

If you need to know how big your USPS parcel can be, we have all the numbers you need below

What size and weight restrictions does USPS have?

The Predefined Package names are drawn from the EasyPost API, so you can better reference how each Predefined Package matches up dimensionally.

Predefined Package Name Dimensions Weight
Card
  • Min: Min: Domestic: 5″ x 3 ½” x 0.007″ International: 5 ½” x 3 ½” x 0.007″
  • Max: 6″ x 4 ¼” x 0.016″
 Must be a flat surface
Letter
  • Min: Domestic: 5″ x 3 ½” x 0.007″ International: 5 ½” x 3 ½” x 0.007″
  • Max: 11 ½” x 6 ⅛” x ¼”
 Maximum weight is 3.5 oz.
Flat
  • Min: 11 ½” x 6 ⅛” x ¼” (must exceed one of these dimensions)
  • Max: 15″ x 12″ x 3/4″
 Maximum weight is 13 oz.
Parcel
  • Domestic: Maximum size for USPS Ground Advantage is 130″ in combined length and girth (distance around the thickest part). Other mail classes maximum size is 130″ in combined length and girth.
  • International: Maximum length + height + thickness combined = 36 inches
 Maximum weight is 70 lbs.
Flat Rate Envelope 12 ½” x 9 ½”
  • Domestic maximum weight is 70 lbs.
  • International maximum weight is 4 lbs.
Flat Rate Legal Envelope 15″ x 9 ½”
  • Domestic maximum weight is 70 lbs.
  • International maximum weight is 4 lbs.
Flat Rate PaddedEnvelope 12 ½” x 9 ½”
  • Domestic maximum weight is 70 lbs.
  • International maximum weight is 4 lbs.
Flat Rate Gift Card Envelope 10″ x 7″
  • Domestic maximum weight is 70 lbs.
  • International maximum weight is 4 lbs.
Flat Rate Window Envelope 10″ x 5″
  • Domestic maximum weight is 70 lbs.
  • International maximum weight is 4 lbs.
Flat Rate Card board Envelope 12 ½” x 9 ½”
  • Domestic maximum weight is 70 lbs.
  • International maximum weight is 4 lbs.
Small Flat Rate Envelope 12 ½” x 9 ½”
  • Domestic maximum weight is 70 lbs.
  • International maximum weight is 4 lbs.
Small Flat Rate Box 8 ⅝” x 5 ⅜” x 1 ⅝” Maximum weight is 70 lbs.
Medium Flat Rate Box 11″ x 8 ½” x 5 ½” Maximum weight is 70 lbs.
Large Flat Rate Box 12″ x 12″ x 5 ½” Maximum weight is 70 lbs.
SoftPack The longest dimension may not exceed 18 inches. Cubic rating will be applied using Length and Width only. See more details on the USPS Cubic Pricing page. Maximum weight is 20 lbs.

Ready to start shipping your USPS packages? EasyPost offers Commercial Pricing to all customers, regardless of volume. Discover how much you can save compared to retail rates today with our USPS Rate Chart.


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