Postal Regulations of Letter Size Mail
If you are designing a postcard or an envelope to be mailed through the United States Post Office then there are a few regulations you will need to follow to ensure that your postcard meets the guidelines required for mailing.

Letter Size Mail

Specifications
Minimum Length: 5 inches
Maximum Length: 11.5 inches
Minimum Height: 3.5 inches
Maximum Height: 6 1/8 inches
Mimimum Thickness: .007 inches
Maximum Thickness: 1/4 inch

Letter Size mail includes:
Postcards, Brochure Self mailers, Newsletters, & anything that falls between the minimum to maximum size and meets the aspect ration requirement.

  




Aspect Ratio
Letter Size Mail must meet the aspect ratio and fall between 1.3 to 2.5 when dividing the height of the mail piece into the length
Addressing

You must leave clear a rectangle measuring 4.25" from right side of postcard or letter and 2.25" from bottom of postcard or letter to allow enough space for an OCR-readable address and/or barcode. Mail permit must be placed above and to the right of the address block. The area to the left of the OCR Read Area should be free of any address information.

If your mail piece address block fails to meet the requirements of the USPS as shown, you may incur additional postage or your mail piece may be rejected by the USPS.


 
First Class / Bulk Mail

First Class mail
First Class mail offers a special rate for postcards.


Postcard Min. Size: 3.5" x 5" x 0.007" thick
Postcard Max. Size: 4.25" x 6" x 0.016" thick

Letter Min. Size: 3.5" x 5"
Letter Max. Size: 6.125" x 11.5" x 0.25" thick

Standard (Bulk) Mail
Standard Mail does not offer a special rate for postcards.

Letter/Card Minimum Size: 3.5" x 5" x 0.0007" thick

Letter/Card Maximum Size: 11.5" x 6.125" x 0.25" thick


Booklets

Letter size mail that are bound by staples or other means must meet the new postal regulations for presorted automated mail.

1) Must meet the letter size and aspect ratio requirements.
2) The address blcok must be located within the OCR read area for letters.
3) Bound edge must be on the bottom or right side of the mail piece.

Specifications
Minimum height: 3"       Maximum height: 6"
Minimum length: 5"       Maximum length: 10.5"

Maximum thickness: .25 inches
Maximum weight: 3 ounces



  

Bottom Bound Edge
Mail pieces with the bound edge on the bottom requires three 1 1/2" non-perferated tab seals as shown. 2 seals on the right edge and 1 seal on the left edge.

Right Bound Edge
Mail pieces with the bound edge on the right requires three 1 1/2" tab seals. 2 seals on the top edge and 1 seal on the left edge