July 2024 Postage Rates For Large Envelopes. The baseline postage rate to mail a flat/large envelope has increased from $1.39 to $1.50 in postage. Mailing & shipping rates for the u.s.

Effective september 16th, usps is adjusting rates for priority mail® and ground advantage®. 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.