$1.30 Stamps for Large Envelopes

In 2020 if you are mailing your "large envelope" wedding invitations or any other letter the post office deems as a large envelope (sometimes called "Flats") and it weighs 3 oz you will need a $1.30 stamp to mail it 1st-class. (The previous price for letters of this size/weight was $1.42. Stamps with that face value will still work, they simply cost few cents more.) Letters are considered "large envelopes" or "flats" if they measure greater than 6-1/8 inches high OR 11-1/2 inches long OR 1/4 inch thick. You can determine if your letter is a standard letter or a large envelope by using our postage calculator, but be sure to double-check the weight of your invitations with your local USPS post office.