Priority Mail Flat Rate Envelope Cost 2024. Effective september 16th, usps is adjusting rates for priority mail® and ground advantage®. Expect a 5% average increase, with some rates going up to $3.10 more.

Costs for the usps ground advantage will vary on the cost of. Learn about the 2024 postage price change for usps services and products, and how it affects domestic and international mail.