Oversize/Underweight Mail

First-Class mail weighing one ounce or less is nonstandard if it exceeds any of the following size limits:

• 11½ inches in length, or
• 6½ inches in height, or      
• ¼ inches in thickness, or        

its aspect ratio (length divided by height) does not fall between 1 to 1.3 and 1 to 2.5 inclusive.

There is an additional charge on each piece of mail that is found to be nonstandard. In addition, pieces that are less than:

• 3½ inches in height, or
• 5 inches in length, or
• .007 of an inch in thickness (thickness of a postcard)

are otherwise non-mailable by U.S. Postal Service standards and are subject to return.

First Class

Any mailable matter may be mailed as First-Class Mail. The following materials are considered First-Class matter and must carry postage at First-Class or Priority Mail Rates:

• Matter wholly or partially handwritten or typewritten (including identical copies prepared by automatic typewriter), originals or carbons, invoices (except when they accompany the matter to which they relate), post cards.
• Matter sealed and closed against postal inspection.
• Bills and statements of account.
• Price lists.
• Any business reply mail     
• Checks, cancelled or not cancelled.

Priority Mail

Priority Mail is First-Class Mail, but stipulates two- or three-day service. The maximum weight is 70 pounds and the maximum size is 108 inches in length and girth combined.

Standard Mail (A)

The following is considered Third-Class Matter:

• Circulars Catalogs
• Booklets Newspapers
• Merchandise Product Samples
• Photographs Printed Matter

Standard Mail (B)

The following is considered Fourth-Class Matter:

• Packages or Parcels Sound Recordings
• Library Materials Merchandise
• Books Films
• Bound Printed Matter

Each piece of Standard (B) Mail must not exceed 70 pounds in weight and maximum size of 108 inches in length and girth combined.