Flat Envelope Postage Rate 2025

Flat Envelope Postage Rate 2025. Download your copy of our postage rate chart and 2025 usps promotions calendar. Square, oversized, or unusually shaped envelope stamps start at $1.19.

Letters (maximum weight 500 grams) for a weight not exceeding 20 gms. For each extra ounce, your 9×12 envelope has to be accompanied by an.