#Standard envelope sizes for mailing download#

The Postal Service uses the word “flats” to refer to large envelopes, newsletters, and magazines. A letter that contains items such as pens, pencils, or keys that create an uneven thickness.A letter that has a delivery address parallel to the shorter side of the mail piece.

A letter that has clasps, strings, buttons, or similar closure devices.

A letter that is more than 4¼ inches high or 6 inches long and is less than 0.009 inch thick.

A letter that has an aspect ratio (length divided by height) of less than 1 ⅓ or more than 2½ (a square envelope has an aspect ratio of 1, making it non-machinable).

#Standard envelope sizes for mailing download#

For a list of non-machinable characteristics, download the non-machinable characteristics (PDF) document. The Postal Service charges extra postage because mail pieces that are rigid, square, or unusually shaped, often jam postal equipment and are difficult to process.

Customers can be unpleasantly surprised that they must pay extra postage when, for example, they mail a square greeting card. No more than 6 ⅛ inches high x 11½ inches long x ¼ inch thick.įirst-Class Mail letters that have one or more non-machinable characteristics will pay a non-machinable surcharge.At least 3½ inches high x 5 inches long x 0.007 inch thick.To be eligible for mailing at the price for letters, a letter must be: If your mail piece does not meet the dimensions above, then the Postal Service considers it a letter. No more than 4¼ inches high x 6 inches long x 0.016 inches thick.

To qualify for mailing at the First-Class Mail postcard price, it must be: Visit the USPS Price List page for current postage and shipping rates.įor additional information, visit the USPS website or use the USPS Postage Price Calculator.