Generally, you’ll need one stamp for each mail shipment, but their price depends on whether you send a letter across Canada, to the USA, or internationally. For the domestic mail, you’ll need a stamp costing $1.07 (for a letter up to 30 g), and a $1.3 stamp for letters weighing 30-50 g. For mail sent to the USA, the same applies to stamps priced at $1.3 and $1.94, respectively. For international letters, the stamps are priced at $2.71 and $3.88, accordingly.