How many stamps would it take to send a letter from Tennessee to London?

Hi,

I write letters for amnesty international and they gave me the following postage rules:

Within the United States:

$0.26 - Postcards

$0.41 - Letters and Cards (up to 1 oz.)

To Mexico and Canada:

$0.69 - Postcards

$0.69 - Airmail Letters and Cards (up to 1 oz.)

To all other destination countries:

$0.90 - Postcards

$0.90 - Airmail Letters and Cards (up to 1 oz.)

To my knowledge, any letter you send abroad is considered to be "Airmail," although that doesn't mean you use a special envelope or anything. So, when I write abroad I just use regular envelopes, paper, and stamps. From Tennessee to London you will need .90 cents worth of stamps.