Mailpiece Design Specifications

Mailpiece Design Specifications

Learn about mailpiece design specifications below. For complete rules and criteria regarding mail piece design, please visit the USPS website »

Minimum Size

If a mailpiece is 1/4" thick or less, it MUST be rectangular and at least 3 1/2" high by 5" long.

All mailpieces MUST be at least .007" thick. Oversize letter-size mail (more than 4 1/4" high or more than 6" long) must be at least .009" thick. Cards that measure more than 4 1/4" high, 6" long, or 0.016" thick are charged postage at First-Class Mail letter rates.

Maximum Size

Maximum size for Standard Mail letter rate is 6 1/2" x 11".

Mailpiece Shape

The shape of your mailpiece can determine the rate you pay. In some instances, certain shapes like squares and tubes are charged a higher rate or a special surcharge because those pieces must be processed manually.  Generally, mailpieces that are 1/4" thick or less MUST be rectangular. Pieces more than 1/4" thick do not have to be rectangular.

You want your mailpiece to catch your customers' attention. However, an odd-shaped mailpiece may not only cost more to design and print, but also may be non-mailable (for example a round postcard) or subject to a surcharge. First-Class Mail letters (1 ounce or less) and Standard Mail letters (3.3 ounces or less) that are square, rigid, or unusually shaped are subject to a non-machinable surcharge of $.21. Standard Mail parcels are subject to a residual shape surcharge.

Ancillary Service Endorsements

Ancillary Service Endorsements tell the Post Office what you would like done with undeliverable mail. If you are using an Ancillary Service Endorsement on your mailpiece please do not use Address Service Requested or Forwarding Service Requested. Your department will be charged a weighted fee for the addresses that are returned. A weighted fee is the price of the piece at First Class Mail rates times 2.472. (A piece that would be mailed at First Class will cost over $1 for each address or piece returned.) Change Service Requested may be a better alternative at $.55 per address returned.

Permit Imprints (Indicia)

Permit Indices allow mailers to send mail without postage stamps or meter strips. The indicia must contain the permit number and mailing class.

Mailings must be deposited at a Bulk Mail Entry Unit or other location designated by the postmaster. Mail must not be deposited in street collection boxes. The Post Office can revoke our Non-profit status and/or Standard Mail Permit if this happens.

If you are having a piece designed to mail Standard Mail but may also mail the piece First Class, have two of the same design printed, one with the indicia and one without. If the piece you want to mail has an indicia preprinted, before you can mail the piece at First Class rates, you will be required to cover the indicia. We will not cover indices because our equipment does not have this capability. This increases your workload and makes your piece look less than professional.