Mailing a standard postcard or standard letter weighing 2 ounces or less from the United States to Canada costs $1.20 in 2016. Letters valued under $400 weighing 3 or more ounces cost more per ounce. The U.S. Postal Service has an international postage calculator to determining overseas postage costs.
Both the USPS and other delivery carriers transport letters and packages from the United States to Canada. Although the procedures and postage rates for letters are fairly simple and straightforward, regulations for sending packages are more stringent and the procedures more complex. The prices are also generally much higher than shipping packages within the United States, and delivery times are much longer due to customs and tax regulations.