postcardBecause there was some confusion in the first Mixed Media Club postcard swap, I’m writing this article, with all the specifications. That way, we can all be on the same page in the future!

What the Dictionary Says:

postcard (ˈpōs(t)kärd/) n.
A card for sending a message by mail without an envelope, typically having a photograph or other illustration on one side.

So, a postcard is something designed to mail WITHOUT an envelope. It has to be sturdy enough, and flat enough, to go through the postal machines, and through all the various hands it takes to get it from me to you, without any covering. If you send a postcard in a clear cello envelope, it’s no longer a postcard. It’s a card in an envelope, and the Post Office will call it a First Class letter.

What the Post Office Says:

According to the USPS, postcards must be:

  • Rectangular. Not square, and not any other shape, and no rounded corners.
  • At least 3.5″ tall, 5″ long, and .007 thick.
  • No more than 4.25″ tall, 6″ long, and .016 thick.

    In order to stay within these restrictions, there should be NO DIMENSIONAL EMBELLISHMENTS used in the creation of postcards.

In addition, there are rules about the back side:

  • Backs should be white, or light colored, so postal machines can read them.
  • The bottom .75″ must be left free of images or text.
  • A 1.18″ square in the upper right corner must be free of images, to hold a stamp.
  • The address of the recipient must be on the right side of the back, no more than 2.25″ from the right edge.


This is how the Post Office wants the backs of postcards to look.

9 thoughts on “What is a Postcard?

  1. I have used cut up file folders in the past. Do you consider that acceptable or do you buy blank postcards?
    Great explanation. Thank you.

    1. Lynne, I’m not sure file folders are heavy enough for my taste, but if you’ve had success with them, go for it. I did my last round of postcards on recycled cereal boxes, but I’ve also used three layers of index cards, and purchased watercolor paper postcard blanks.

    1. There is no yes or no, “have to” answer to that question. Does the back look finished if you don’t cover it? Can you write on it? Is it light enough for it to pass successfully through a postal machine, and have its address read? Is the back free of unintentional paint blotches?

      At a certain point, you have to make choices based on what’s in front of you, and not based on what I think, way over here, unable to see what you’re doing.

  2. Is it acceptable (by the USPS) to send postcards within clear envelopes? Normal postcards are about A2 size, I think.

    1. As it says in the definition above: postcards are items sent without an envelope. Once you put it in an envelope, even if that envelope is clear, it becomes a First Class Letter.

  3. thanks for the detailed and concise explanation of “what is a postcard”. Keeps everyone on the same page.

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