Usps Postage Rates 2024 Large Envelope. 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 at 24 cents per additional ounce. Washington, dc — the u.s.
Washington, dc — today, the u. Priority mail, including priority mail flat rate shipping products, has fast shipping times (1, 2, or 3 business days) with.