Postage for a 5x5 square postcard?

I have a square postcard, measuring 5x5. This is to be sent inside the USA so should I use a postcard stamp or one regular forever USA stamp? Thanks in advance!

i believe a non-machinable stamp (the purple buttery stamp) or equivalent value must be used because of the square shape makes it not able to go through automation. the non-machinable rate is currently 99¢ worth of postage (ex. a forever stamp + 39¢) but may go up on the 23rd, when most usps rates are scheduled to go up.


a postcard with that measurements would be a forever stamp (60¢). non-machinable would be if was thicker than ¼ inches or in a plastic cover. greeting cards of that measure pass this, why not a postcard.


if it is square-sized, the piece of mail is still considered non-machinable:

with that said, it may arrive fine with just a forever stamp but i tend to err on the side of caution and put extra postage on to make sure postage isn’t due to the recipient.


Got it. Thanks!

that is correct for a 1st class letter, not a postcard. i do not know how to copy these webpage, but is a link to the price of a 1st class postcard, not a 1st class letter rate.

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Actually, @sarahaeyo is correct. Any card bigger than 4x6 is classed as first class letter, and square letters are non-machinable. That’s not to say one can’t often get away with just a forever stamp, but the correct rate is non-machinable.

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Thanks! I will be sure to add the correct amount of postage.

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USPS changed the maximum dimensions for postcards, it’s up to 6x9 now:

I agree that square cards needs a non-machinable surcharge so I’d put 48c (postcard rate) + 40c (non-machinable surcharge) as sufficient postage.

That’s for commercial mail only. Private postcard max size remains 4x6.

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I just noticed your 48¢ + 50¢ calculation. The surcharge is always on top of the first class letter rate. Non-machinable postcards do not qualify for the postcard rate and regular letter rates apply regardless of size.

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You are right, I looked in the wrong category, my bad!

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Where on a greeting card does it state additional postage needed? I have large greeting card
envelopes but it is not stated anywhere.