How much would it cost to send a postcard internationally?
They may not exceed 3.5 ounces. Postcards cost $1.20 to mail and cannot exceed one ounce. Sending large flats can cost anywhere from $2.38 to $36.46, while packages range from $6.39 to $38.43.Flats and packages may not exceed 64 ounces, and packages cannot be more than 24 inches long and 36 inches in combined dimensions.hey may not exceed 3.5 ounces. Postcards cost $1.20 to mail and cannot exceed one ounce. Sending large flats can cost anywhere from $2.38 to $36.46, while packages range from $6.39 to $38.43.