July 2024 Postage Rates For Large Envelopes. 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. The usps filed notice with the postal regulatory commission for price changes that will be taking effect on july 14th, 2024.

The changes will raise mailing services product prices approximately 7.8 percent. These changes will affect the cost of sending letters and.