Preparing International Shipments

Size & Weight Requirements

  1. Postcards

    Postcards must be rectangular to qualify for First-Class Mail® prices.

    Oversized postcards will be charged as letters or large envelopes.

    Size Requirements:

    • Height: 3 1/2" min. / 4 1/4" max.
    • Length: 5 1/2" min. / 6" max.
    • Thickness: 0.007" min. / 0.016" max.
  2. Envelopes

    Must be rectangular to qualify for letter prices.

    Size Requirements:

    • Height: 3 1/2" min. / 6 1/8" max.
    • Length: 5" min. / 11 1/2" max.
    • Thickness: 0.007" min. / 1/4" max.
    • Max. Weight: 3.5 oz.
  3. Large Envelopes (Flats)

    Must be rectangular, flexible, and uniformly thick to qualify for flat pricing.

    Large envelopes that exceed size requirements will be charged the applicable First-Class Package International Service® (small packet) price.

    Size Requirements:

    • Height: 12" max.
    • Length: 15" max.
    • Thickness: 3/4" max.
    • Max. Weight: 15.994 oz
  4. Packages

    If you’re not using a USPS-produced Priority Mail International® Box, the total girth (distance around the thickest part) of your package is up to 108".

    Measuring Package Girth

    The total weight of your package may not exceed 70 lbs, though, the destination country may have lower weight limits.

    See Weight Limits by Country and Service

Restricted & Prohibited Items

Any items that are prohibited from being mailed domestically are also prohibited from being sent internationally.

View All Prohibited Items


Restricted Items

  • Cigars
  • Lithium Batteries
  • Medical Devices
  • Medicine or Drugs

International Address & Label Formats

  • Print complete and correct addresses clearly in capital letters with a pen or permanent marker.
  • Do not use commas or periods.
  • Mark the package “Fragile” or “Perishable” when appropriate.
  • If you’re reusing a box, make sure all other addresses are covered or blacked out.
  • Affix sufficient postage to avoid charges for additional postage due or delivery delay.

Additional Address Information

View Standard USPS Abbreviations
Guidelines for Addressing International Mail & Packages

Complete a Customs Form

You generally need a customs form for all international mail and parcels. Which form you need depends on the service you’re using and the declared value of your package.

Complete a Customs Form

Pack the Box

Choose a sturdy box with enough room for cushioning material around the contents to protect fragile items and prevent items from shifting.

Tape your box shut and reinforce the seams with 2"-wide packing tape. Do not use cord, string, or twine because it gets caught in the mail processing equipment.

Order Supplies

Tips for Preparing Shipments

Full Letter Mail Standards Expand Collapse FAQ question

Meeting one or more of the following are considered nonmachinable and subject to a surcharge.

  • Envelope has clasps or similar stiff closures.
  • Envelope contains items causing thickness to be uneven.
  • Address is written parallel to the short side of the envelope.
  • Envelope is too rigid.
  • The aspect ratio of the envelope (length divided by height) is less than 1.3 or more than 2.5.
  • Is polybagged, polywrapped, enclosed in any plastic material, or has an exterior surface made of a material that is not paper.
  • Envelopes more than 4 ¼ inches high or 6 inches long and the thickness is less than 0.009 inches.
  • Is a self-mailer or booklet not prepared according to standards.

For Priority Mail International Flat Rate® Envelopes, the weight limit is 4 lbs. Large envelopes that do not meet the above standards must pay parcel prices.