The price of a first class stamp will increase by 1p to 64p and second class by 1p to 55p from March 29.
Royal Mail said it had "carefully considered" the impact on customers and its own business before deciding to apply the "smallest possible increase" in stamped letter prices.
The price of large letter stamps will also rise by 1p.
Royal Mail said: "We believe these changes are necessary to help ensure the sustainability of the Universal Postal Service."
The group said its stamp prices were among the best value in Europe.
The price of a first class stamp in the UK remains well below the European average of 78p, and below the 64p figure for second class letters, said Royal Mail.
The UK also has the highest quality specification of any major European country, it said.