It costs a minimum of $1.15 to send a postcard or standard letter from the United States to Scotland via First-Class Mail as of 2015. The complete cost may vary depending of the size, shape, weight and machinability of the letter.
An extra surcharge is assessed on letters that are considered nonmachinable as of 2015. This includes oddly or unevenly shaped letters and letters that are extremely rigid or that have incorrectly placed addresses. Letters that are oversized, have over $400 worth of value or are over 3.5 ounces in weight are not classified as letters as of 2015 and thus use package pricing. First Class Mail does not have a guaranteed delivery date.