Postage Rates 2024 Flat Envelope. Changes by usps for postcards, flats & letter size. 2 pounds priority mail retail zone 4 postage plus 1.15 letters that meet one or more of the nonmachinable characteristics in dmm 101.1.2 are subject to the $0.46 nonmachinable surcharge.

Washington, dc — today, the u. The baseline postage rate to mail a flat/large envelope has increased from $1.35 to $1.39 in postage, but the price for each additional ounce also stayed the same.