The
United States Postal Service
The United States Postal Service (USPS), also known as the Post Office, U.S. Mail, or simply the Postal Service, is an independent agencies of the United States government, independent agency of the executive branch of the federal governmen ...
uses the words "flats" and "nonletters" interchangeably to refer to large envelopes, newsletters, and magazines.
Size restrictions
To fit the definition a flat must:
*Have one dimension that is greater than 6-1/8 inches high OR 11-½ inches long (the side parallel to the address as read) OR ¼ inch thick.
*Be no more than 12 inches high x 15 inches long x ¾ inch thick.
*Weigh no more than 13 ounces.
Furthermore, the item must be somewhat bendable: see the USPS Domestic Mail Manual for exact details.
This general rule does not apply to:
Automation rate flats
Automation describes a wide range of technologies that reduce human intervention in processes, mainly by predetermining decision criteria, subprocess relationships, and related actions, as well as embodying those predeterminations in machine ...
and
Standard Mail Enhanced Carrier Route flats.
Postage
The maximum size for a flat provides enough room to enclose much material. An issue, however, is that the higher the weight the higher the postage, especially for First-Class Mail.
External links and references
Domestic Mail Manual 101.2 Flats Physical Standards
United States Postal Service
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