What are the USPS mailing limitations for postcards?

USPS sorts mail into size bands, and those bands decide whether a card mails at the lower postcard rate or at letter and flat rates. Staying inside the postcard dimensions keeps postage cheaper, while going larger buys more space at a higher rate.

• A popular size like 4 x 6 qualifies for postcard rates.
• Sizes such as 5 x 7 or 6 x 9 usually mail at letter or flat rates.
• Confirm current dimensions and rates with USPS before a large mailing.

Postcards mailed on their own with postage and no envelope must meet these size rules. Custom die-cut shapes may not qualify for automated postcard rates, so check the shape and exact dimensions against current USPS rules before printing.