Yes , as long as they equal the value of the correct postage to Germany You cant just put on a (regular first class) 45cent stamp. First, then, find out the correct postage amount for Germany.
Regular first class international postage from USPS is $0.98.
One first class postage.
Enough stamps to equal first class postage of 49 cents, or a Forever stamp. It will also have an address.
First Class Postage is 44 cents for the first ounce.
First ounce for First Class Postage was .29
Postage to Europe from the US is 98 cents for a one-ounce letter.
There is only one Forever Stamp, it pictures the US Liberty Bell and says First Class Postage. It is good only for the first ounce of a letter, anything more in weight requires additional postage. There are many other non-denominated stamps that may say First Class Postage, but they are not Forever Stamps, they were created for a specific rate. These stamps are still valid for that amount of postage, but they must be supplemented to make the full rate necessary.
It reqires 49 cents in postage to send a first class letter within the U.S.
The entire purpose of the Forever Stamps was that you can use them for one ounce of First Class Postage forever. No additional postage is necessary.
44 cents is the going rate for an ordinary first class stamp.
In the US for a first class mail letter (1 oz.) it is .44¢