Postage for 9x12 Envelope - Stamps Required, Cost
For a 9×12 envelope with 2 Oz weight, you need 2 Forever Stamps and 1 Additional Stamp. Similarly, you can post a 9×12 envelope with a maximum weight of up to 13 Ounces. How Much is the Cost of 9×12 Envelope Postage. There are many things that decide the cost of posting a 9×12 envelope.