Question: how many forever stamps to put on a letter?
Answer: Avoid placing two Forever Stamps on a mail piece for heavier mail. Additional ounces are much cheaper costing only $0.15 per additional ounce rather than $0.55 for a one ounce letter. If you add two Forever Stamps to a 2 ounce letter, you would be paying for an item that should only cost $0.70.