Postage Rates 2024 Additional Ounce Postage. 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. Postal service filed notice with the postal regulatory commission of mailing services price changes to take effect july 14,.

See forever postage stamp prices and other postage rates. Here are the highlights of.