I'm mailing a small package whose postage comes to $2.52. I am pretty sure that I can use seven forever stamps and that at the current 42 cent value that will be sufficient postage (7x.42= $2.52). This is based on the USPS page http://faq.usps.com/eCustomer/iq/usps/request.do?create=kb:USPSFAQ&view()=c{52eabcb0-efa5-11dc-67fc-000000000000} which states: "The postage value of the Forever Stamp is always the First-Class Mail single-piece 1-ounce letter price in effect on the day of use (the day of mailing). Forever Stamps purchased before May 12 are now worth 42 cents postage. Forever Stamps affixed to 1-ounce letters do not require additional postage. As always, customers still need additional postage for letters weighing over 1 ounce, letters subject to the nonmachinable surcharge, and mailpieces that are larger than letter-size." Typo correction: As the math will show, six stamps not seven would be needed.