Fastest and most costly. This service should be used only when absolutely necessary. Express mail service is available to most foreign countries. Contact the Mail Customer Service Branch for delivery schedules and information.
First Class Mail
Any mailable item weighing 13 ounces or less. Items such as letters, post cards, official notes, and checks should be mailed via First-Class Mail.
First Class Mail - Mail Shape Helps Determine Cost
- Maximum length 6” - Minimum length 5”
- Maximum height 4-1/4” - Minimum height 3-1/2”
- Maximum thickness 0.016” - Minimum thickness 0.007”
- Maximum weight 3.5 ounces
- Maximum length 11-1/2" - Minimum length 5”
- Maximum height 6-1/8” - Minimum height 3-1/2”
- Maximum thickness 1/4” - Minimum thickness 0.007”
If your letter exceeds any of the above factors it will be classified and priced as a large envelope (flat).
Large envelopes (flats):
- Maximum weight: 13 ounces
- Maximum height: 12" - Minimum height 6-1/8”
- Maximum length: 15” - Minimum length 11-1/2”
- Maximum thickness: 3/4"
A large envelope that exceeds any of these dimensions will be classified and priced as a package (parcel). Large envelopes must also be flexible, rectangular and uniformly thick. A large envelope that exceeds 13 ounces is classified and priced as Priority Mail.
First Class Packages:
- Maximum weight: 13 ounces
- Maximum size no more than 108" in combined length and girth
Packages that exceed 13 ounces are classified and priced as Priority Mail.
Any mailable item weighing over 13 ounces but less than 70 pounds. When the speed of Express Mail is not needed, and preferential handling is desired, use Priority Mail.
Bound Printed Matter
Consists of advertising, promotional, directory or editorial material (or any combination of such material) up to 15 lbs. The material must be bound by permanent fastenings such as staples, spiral binding, glue or stitching. Loose-leaf binders and similar fastenings are not considered permanent. Contact the Mail Customer Service Branch when planning to mail this material.
Mailable matter not required to be mailed as First Class or Priority and weighing 16 ounces or more. Packages mailed within the U.S. may weigh up to 70 pounds.
Mailable matter not required to be mailed as First-Class weighing more than 5 ounces. This class of service can only be used when it is mailed from a library, academic institution, museum, non-profit or similar organization and addressed to schools, colleges, universities, public libraries and nonprofit religious, educational and scientific organizations or associations. Library Mail cannot contain advertising or other non-media materials except for a packing slip.
Mailable matter not required to be mailed as First-Class weighing more than 5 ounces. This service should be used for items such as CDs, videos, books, scholarly bibliography, printed music, bound volumes of academic thesis in typewritten or duplicated form, periodicals and sound recordings. Media Mail cannot contain advertising or other non-media materials except for a packing slip.