When does a Postcard Become a Letter in the USA?! (This is NOT a koan)

Saturday, June 26, 2021 - 22:25 (UTC -5)

Good evening, Everyone:

This topic concerns primarily people who send postcards from within the USA to addresses also within the USA.

I’ve been mailing these postcards recently =>


They’re 5 x 7 inches.

I was at my local post office this afternoon to mail a few postcards, including one of these Bucks County arts postcards.

The postal clerk showed me a template detailing the dimensions of various kinds of mail pieces. To use the domestic postcard rate (currently at $0.36 USD), a postcard can be no larger than 6 x 4 1/4 inches (and no thicker than 0.016 inches). If it’s larger than that (up to the maximum size allowed for postcards of 11 1/2 x 6 1/8 inches x 1/4 inch thick), the required postage then becomes $0.55 USD, the price for a First-Class Letter.

She told me that while technically a 5 x 7 card should have First-Class Letter postage on it, most US Postal Service staff will let such a card pass with a regular domestic postcard stamp on it PROVIDED it is obviously “personal communication”, not “commercial or business” communications. There’s no guarantee they’ll always let such “inappropriately”-stamped postcards pass and we (senders) will never know what happened to our card if it doesn’t arrive unless we had a return address on it somewhere in order for it to be “Returned to Sender” for the proper postage. There’s also the very remote chance that the postal service might deliver the card anyway but “bill” the recipient for the postage difference upon delivery.

So if it really-really has to make it, stack the odds in your favor with First-Class postage for anything bigger than 6 x 4 1/4. Who knew?

In the end, this information was “anticipatory” because the 5 x 7 card I mailed today was to a friend in Mallorca (Spain).

Happy Postcrossing,



I have no idea… I only put 0.55 on something like 8x10 or long postcards. Maybe I should start putting my address on them now. :face_with_hand_over_mouth:

When in doubt, put extra postage. And make sure your penmanship is very clear on the address.

I have issues with your wording, but I am particular with regard to language. A postcard becomes a letter when you place it inside an envelope, and send it via that means. Otherwise, it is always a postcard. That being said, the USPS has very specific guidance with regard to size of the card (and, in fact purpose of the communication) as it pertains to the amount of postage required for postcards.

Note that you do not have to use “postcard specific” stamps to achieve the required level of postage required, you can use stamps of any denomination to meet the required cost. They just issue postcard stamps to make it easier for you.

Here’s the current guidance:

And here’s the latest version of the template:

I wish they sold those templates, I’d love to have one. Most post offices are short on them, but usually at least one of the clerks has one. I have a taped together one that is “Rev A” from photocopies a postal clerk made for me.

The best approach for successful delivery is to use the proper amount of required postage in accordance with the USPS regulations. I have mailed many larger cards successfully domestically, they just have to have the required amount off postage on them.

What is a koan?

I generally don’t mail postcards within the US, but if I do, they are usually the 4X6 size. Only a suggestion, but don’t get a clerk involved with your mail. Put the appropriate postage on the card and mail it.

This money-losing organization (USPS) is diabolical with the ways to strangle you with excruciating minutiae. They will ding you whenever they can.

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Yeah, 6x4.25 inches. Of course if you send a 5x7 postcard internationally its $1.30, same as a letter of 1 ounce (28 grams) or less, so I save the bigger cards for my overseas correspondents and the regulation sized cards for domestic use.