The price of sending a letter will rise by 1p on 29 March.
The cost of a first class stamp will go up to 64p, while the cost of second class will rise to 55p.
The Royal Mail said it had carefully considered the impact on customers, before deciding to apply the “smallest possible increase”.
It said the rise was necessary to help ensure the sustainability of the universal service – the ability to deliver all over the UK for one price.
It added that its prices were amongst the best value in Europe.
Full details of the price changes can be found here.