You only have to provide normal, domestic postage on mail going to an APO or FPO address. The United States Post Office delivers APO and FPO mail to a military ports, and the military takes over from there, transporting the mail via military cargo aircraft to the overseas location/Navy ship.
The postage amount is determined by the weight and size of the package according to USPS pricing charts. You can visit www.usps.com to utilize their postage calculator to get an idea of what your specific package may cost. Please remember to include our handling fee and insurance coverage fees in your math.