The price of a first class stamp will be increased by 6p to 76p and the price of a second class stamp will rise 4p to 65p, Royal Mail said.
The increases are double those of last year - making posting a letter more than twice as expensive as in 2006.
Royal Mail said despite the rises "stamp prices are among the best value in Europe".
Stephen Agar, managing director of letters at Royal Mail said: "We are operating in a tough market at present, under the threat of making a loss by 2021.
"These price increases will help us maintain the quality of service that is expected by our customers, while supporting the universal service."
Royal Mail said it does understands many companies and families find it hard in the current economic environment.
"As a result, we have considered any pricing changes very carefully and in doing so have sought to minimise any impact on our customers," a statement read.
The price rises follows hikes last year of 3p on a first and second class stamp.
Royal Mail said it was operating in a "challenging business environment".
"These changes are necessary to help ensure the sustainability of the one-price-goes-anywhere Universal Service," the company said.
The cost of Royal Mail stamps will increase from March 23.
