Post Cards… and Letters… and Flats, Oh My!

Whether you are mailing First Class or Standard (bulk advertising) mail, the US Postal Service assesses postage rates, in part, by the “processing category” of your mail piece.


Knowing what category your mail piece will be placed, is extremely important when designing your mail piece. We see instances all the time where, a very slight change in the height or width of your mail piece (usually 1/8th of an inch or less) would result in postage savings of as much as 10 to 15 cents each! Also, each of the different processing categories have different postal regulations as to eligibility for special bar coded postage discounts and preparation requirements. So, here’s the scoop on how the post office will assign a processing category to your mail.


When you read the word “post card” in the DMM (Domestic Mail Manual), they are referring to the official definition of a USPS “postal card”. The rest of us think of a “post card” as a single sheet of card stock with color, text or pictures on the front and back of the card with an area to put the name and address of the person you are mailing to. In order to qualify for a presorted first class “post card” rate (as, there is no “post card” rate for standard mail), the size and dimensions of your mail piece must be at least 3 ½  inches high and 5 inches long, but not more than 4 ¼ inches high and 6 inches long.


Most of your standard mail (advertising mail) post cards will exceed those dimensions and will be categorized by the post office as a “letter” sized piece. For instance, if you design a large postcard that is 6 inches high and 11 inches long, it will be assessed a “letter-rate”.


A “letter” sized piece is defined by the post office as a mail piece that is at no more than 6 1/8 inches high and 11 ½ inches long. “Letter” sized rates are the most common for standard mail. If your piece is taller than 6 1/8 inches, your mail piece will be placed in a much more expensive postage category called “Flats”. So, be careful!. I can’t tell how many pieces we’ve seen come in at 6 ¼ inches high (1/8 of an inch too high). In most cases, the aesthetics of the piece would not be affected by shaving off that 1/8 of an inch. Especially if it saves you an extra 10 to 15 cents per piece in postage.


“Flats” are the more expensive postage rate and consists of any mail piece that is taller than 6 1/8 inches high or wider than 11 ½ inches long.


So now that you know the way that the Post Office will categorize your mail piece, you can use that information during your mail piece design stages to insure the best possible postage.