Postage for letters or packages to an FPO address is the same as the domestic U.S. rate, according to the U.S. Postal Service. For a first-class letter weighing an ounce or less, the rate is 49 cents, as of 2014.
Domestic postage rates apply to and from all APO and FPO military addresses, no matter where they are located. Not all items can be shipped to FPO addresses. Alcohol, cigarettes and substances that can explode are examples of things that cannot be sent by mail. Senders to a military address also should be careful to address the mail properly, including the service member's full name, unit and zip code, if one has been assigned. If needed, a customs form should be accurately and completely filled out, or the package may be delayed.