Mailpiece Definitions and Sizing

The May 2007 USPS Rates take into account size and shape of packages and envelopes when determining pricing.

The mailpiece pop-up is the first stop in determining postage rates. You can select from one of seven different types.

Postcard
Perfect for picture postcards and other rectangular mailpieces printed on card stock with no envelope. Cards must fit the following dimensions or they will be considered oversize postcards and subject to First-Class mail rates:

Letter Envelopes
To avoid paying a premium for a mailpiece that is considered "non-machinable" or "oversize", make sure your piece falls within the following guidelines:

Large Envelopes (Flat)
Oversize mailpieces weighing one ounce or less require a special postage amount because the piece must be handled manually. The Postal Service uses the word "flat" to refer to large envelopes, newsletters, and magazines. The words are interchangeable. Whatever you call them, a mailpiece is considered oversize if it meets the following:

- Has one dimension that is greater than 6 1/8" high OR 11 1/2" long OR 1/4" thick.
- Is no more than 12" high x 15" long x 3/4" thick.

Package
When your mailpiece exceeds the limits for a large envelope, it is considered a package. Furthermore, a package's length plus girth cannot exceed 108".

Oversized Package
If your package's length plus girth exceeds 108 inches but does not 130 inches, it is considered an Oversized packages. Oversized packages may only be sent via Parcel Post and may not be sent internationally.

Worried about sizing?

Don't be. If you type in the length, width and thickness of a mailpiece, Endicia for Mac will automatically select the right mailpiece type.

When should I type in the dimensions of something I'm mailing?

Sizing basically affects two things; odd-shaped letters and larger packages sent Priority Mail or Parcel Post.

Odd shaped envelopes, such as a square 5" x 5" greeting card are subject to non-machineable rates. If in doubt about an envelope, type in it's dimensions and Endicia will do the right thing.

Larger packages for Priority Mail are ones who's volume exceeds one cubic foot. An easy way to remember this is "if it fits in a mailbin, it's okay, otherwise measure it." All USPS-supplied envelopes and boxes for all mail classes do not need to be measured.

Larger packages for Parcel Post are those who's length plus girth (girth is two times height + width) exceeds 108".

The girth limit for all packages except Parcel Post is 108".

Flat Rate Envelope
Flat Rate Envelopes are supplied by the USPS and must be used when selecting this mailpiece type.

Flat Rate Boxes
Flat Rate Boxes are supplied by the USPS and must be used when selecting this mailpiece type.