Although the time frame may vary, on average, letters traveling through standard mail from the United States to Canada take four to seven days to reach their destination. The variables that may affect the delivery include the customs process, the amount of mail delivered and weather conditions.
Exact delivery times are not guaranteed by the U.S. or Canadian post offices when sent through standard mail options. However, when selecting air mail or priority mail to deliver a letter or package, the delivery time may be less than four to seven days. Customers cannot opt for certified mail options when sending mail to Canada.