holiday cards and xtra postage

i mailed my holiday cards and was told i need more than the normal postage (they're 5.5" x 5.5"). any idea how much more they may be. i'm trying my best to avoid post office lines. thanks!

From Snapfish

How much is postage for a square envelope?
Square cards require additional postage. Flat photo cards have square
envelopes that are charged a "non machinable surcharge" in addition to
regular postage by the USPS. That surcharge is 20 cents for any piece of first class mail as of August 2012.

If you have a kitchen scale, you can weigh one or more of the envelopes, depending on whether they are all the same weight and determine what the postage should be.

usps.com has a postage calculator that might tell you

the post office in Union near 22 (I think w chestnut st) used to have a self service kiosk where you could weight things...but I haven't been there is a while..i think livingston also

Regardless of the weight, square envelopes require the extra postage because they are not capable of being handled by the machines.

per usps.com, postage for a 1-ounce square envelope is 71 cents (49 cents regular first class plus 22 cents for the "bad" envelope).

thx everyone. yes, i think these do not fit into the auto-sorter...therefore require more postage. i called shutterfly & their rep said it varies from which post office i send them from??? (didnt jive w/ my thinking, but maybe he knows more than i do here!)

my guess is some post office will just allow them thru without the extra postage while others follow the rules

We were caught in that trap one year.  We mailed out cards (square) we had bought that summer on our vacation in London (Harrod's year-round Christmas shop).  We thought we were so clever until they all came back with "postage due".