To qualify for the $0.61 rate, your card must be a minimum of 3.5" x 5", a maximum of 4.25" x 6", and between 0.007" and 0.016" thick.
If your postcard is larger than 4.25" x 6", it is automatically classified as a letter and will cost the standard letter rate ($0.78). buy postcard stamps
Not all mail needs a standard letter stamp! Postcards get a special, lower price tier from the United States Postal Service (USPS) . To qualify for the $0