As of 2014, it takes three regular postage stamps to mail a letter from the U.S. to Canada. It costs $1.15 to mail a letter to Canada from the United States as of 2014.
Each postage stamp is worth 49 cents as of 2014. Therefore, it takes three of them to cover the cost of $1.15. However, that is more postage than is needed to mail the letter, as the three stamps are equal to $1.47. Stamps in smaller amounts, such as 4-cent stamps or postage stamps can be purchased to help cover the cost of the letter instead of using all regular postage stamps. Also, the letter can be mailed from a post office for the exact amount.