The shape of a mail piece
impacts the prices you pay for First-Class Mail letters, large envelopes
("flats"), and packages ("parcels").
Post Cards
Maximum length: 6"
Maximum height: 4 1/4"
Maximum thickness: 0.016"
Letters
Maximum weight: 3.5oz
Maximum length: 11 1/2"
Maximum height: 6 1/8"
Maximum thickness: 1/4"
if your letter exceeds any of
these dimensions it will be classified and priced as a large envelope (flat).
Large
Envelopes
Maximum weight: 13oz
Maximum length: 15"
Maximum height: 12"
Maximum thickness: 3/4"
If your large envelope
exceeds any of these dimensions, it 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.
Packages
Maximum weight: 13oz
Maximum size no more than 108" in combined length and girth
A package that exceeds 13
ounces is classified and priced as Priority Mail.
