23 août 2023 · If the size of a large envelope is from 1 ounce to 2 ounces, the price of the Large Envelope postage will be $1.46 which is calculated as $1.26 for two Forever Stamps and $0.20 for one additional Stamp. For a 3 Ounces Large envelope, you will have to pay $1.66 i.e $1.26 for two Forever Stamps and $0.20 each for two additional Stamps. Similarly.