A standard-size letter from the United States to Germany that weighs 1 ounce or less will cost $1.15. For heavier letters and letters addressed in unusual envelopes, postage costs rise.
Each extra ounce or fraction thereof is somewhat more expensive. For instance, postage for a letter weighing up to 2 ounces costs $2.13 since the first additional ounce costs 98 cents. The price is increased by 99 cents for each additional ounce.
International letters with particular features, such as an aspect ratio of less than 1.3 or more than 2.5, extreme stiffness, or a delivery address parallel to the shorter dimension of the letter, are subject to a nonmachinable surcharge of 21 cents from the post office. USPS.com has information about postal rates.