USPS classifies a 9″ x 12″ envelope as a “flat.” At this writing, the postage rate for flats is $1.00 for the first ounce, and $0.21 for each additional ounce. So the postage required for an 8-ounce flat is $2.47.

Today, you can purchase stamps at a variety of locations, such as convenience stores, grocery stores and even warehouses. Reselling stamps is not illegal. Although you need approval to act as an official contractor or participate in USPS programs, you are free to resell your new or used postage stamps.

You can use more than one Forever Stamp if you need to send a package or a letter that weighs more than an ounce. So if you paid $0.49 and the rate rises to $0.50, you can put two Forever Stamps on a package to get $1.00 worth of postage. You can also use Forever Stamps to send letters internationally.

legal size envelope (9 ½” x 15”), you will need two Forever stamps for a total cost of $1.10. There are also extra postage fees for each additional ounce. For a Manila envelope weighing less than an ounce, you will need two Forever stamps.

Solved. Short Answer: One $0.55 First-Class Mail stamp covers one ounce. However, you do not need one stamp per ounce. First-Class Mail prices anything above one ounce at an additional $0.15 per ounce ($0.70 for two ounces, $0.85 for three ounces, etc.), and you can purchase Additional Ounce stamps for $0.15 each.

rates will not increase and will remain at $1.00 (no change from 2020). Each additional ounce will cost $0.20 (no change from 2020).

As we were talking that the cost of the postage of the large envelope of size like 9×12 has changed. The first ounce of a 9×12 envelope should use two Forever Stamps (equivalent to $1). Besides, you have to pay the extra stamps for each additional ounce equivalent to $0.20.