New USPS Rules for Folded Self Mailers (FSM)

Effective Date: January 5, 2013

United States Postal Service® (USPS®) implemented new regulations for folded self-mailers (FSM’s) and other unenveloped pieces. These new rules do not apply to cards, envelopes, booklet style letters or mail pieces designed to carry discs.

The Changes to Folded Self Mailer Dimensions and Folding:
  • Length: A minimum of 5 inches and a maximum of 10 1/2 inches.
  • Height: A minimum of 3 1/2 inches and a maximum of 6 inches.
  • Thickness: A minimum of 0.007 inch; (0.009 inch if the height exceeds 4 1/4 inches or if the length exceeds 6 inches); the maximum thickness is 1/4 inch.
  •  Maximum Weight: 3 ounces.
  •  Rectangular, with four square corners and parallel opposite sides.
  •  Within an aspect ratio (length divided by height) of 1.3 to 2.5, inclusive.
  •  Maximum number of panels, bi-fold, tri-fold and oblongs: 12 for FSM’s constructed of non-newsprint paper
  •  Exception: Quarter folded self-mailers made of a minimum of 100 lb book grade paper may have 4 panels and those made of 55 lb newsprint must have at least 8 panels and may contain up to 24 panels.
  •  The final fold must be at the bottom for all designs except oblong style pieces. For oblong-style FSMs the final fold is on the leading edge. Tabs cannot be placed on the bottom open edge of an oblong-style FSM.
Sealing Method Changes:

Folded self-mailers must be sealed using tabs or glue. The size and number of tabs required is determined by the weight of the mail piece and optional design elements. Please see attached file for details on folding, tabbing positions, and paper weight.

  • When using tabs on basic folded self-mailers the following applies:
  • Mailing pieces Up to 1 oz require 2 tabs at 1″ diameter
  • Mailing pieces Over 1 oz require 2 tabs at 1.5″ diameter.
  • Some die-cutout mailing pieces require 2-3 tabs at 2” diameter.
  • Tabs cannot be placed on the bottom open edge of an oblong-style FSM.

The size and quantity of tabs will be determined by the weight of the mailing piece as well as the paper stock used. Glue may be used as an alternate sealing method when applied according to the standards for Folded Self-Mailers (FSM).

Tabs may be made of paper, translucent paper, vinyl or plastic. Perforated tabs are now prohibitied. The minimum number of tabs required is 2 and the minimum size is 1” depending upon weight of the weight of the mail.

After January 5, 2013, folded self-mailers that do not meet these requirements will be assessed postage as follows:

  •  First-Class and Standard Mail mailers will pay non-machinable prices.
  •  Periodicals mailers will pay non-barcoded prices.


Print Strategy strongly encourages mailers to review these new regulations and start making plans for any necessary design changes to future mail pieces.

Further information

For more detailed information on these new rules, please contact Print Strategy or check the Folded Self-Mailer landing page on the RIBBS web site.