Our 5 x 7 products do not require any extra postage. Our 5.25 x 5.25 square designs, however, do require additional postage due to USPS regulations when you use a square envelope. Alternatively, we offer a rectangular envelope with a fitted pocket for square cards at no additional charge. Choose this option when placing your order to avoid additional postage prices. If you decide to use square envelopes please be sure to check with your local post office or visit usps.com for current postage rates to mail square envelopes.