Postcards have their own postage rate, cheaper than a letter — but the discount only applies when the card meets USPS postcard dimensions. Here is how to know which stamp your card actually needs, without guessing at the mailbox.
The postcard rate applies when
- The card is at least 3.5 x 5 inches and no larger than 4.25 x 6 inches.
- It is rectangular, on uncoated or matte card stock thick enough to survive handling.
- Nothing is attached to it and it is not in an envelope.
A standard 6x4 printable postcard — like the ones in our printable snail postcard packs — sits exactly inside this window, which is why 6x4 is the size we design for.
When a postcard needs letter postage instead
- Oversized cards. Anything bigger than 4.25 x 6 inches mails at the letter rate, not the postcard rate.
- Square cards. Square mail is non-machinable and costs extra.
- Cards in envelopes. The moment it goes in an envelope, it is a letter.
- Lumpy or decorated cards. Buttons, string, or thick embellishments make it non-machinable.
International postcards
Postcards to other countries use the international First-Class Mail rate — one Global Forever stamp covers a postcard to most destinations.
Check the current rate, not a memory
Postage rates change. Always confirm the current postcard and letter rates on the official USPS prices page before stocking up on stamps. If you mail often, the online postage tools we reviewed print exact postage from home so you never under-stamp.