A national survey has found one in three borrowers do not know what mortgage rate they are paying and an even greater number can only approximate the figure.
The research found 33 per cent of homeowners were unaware of their rate and 44 per cent could only estimate the figure, with borrowers in Wales least likely to know what they pay for their mortgage.
The Which? Mortgage Advisers survey questioned more than 3,500 borrowers in June, and found those who lived in the capital and the young were best informed of their rate.
The survey found 80 per cent of Londoners knew their exact or approximate mortgage rate, alongside 74 per cent of those aged 18-24 years old.
Meanwhile, the survey found one in four respondents sat on their lender’s standard variable rate (SVR).
Of borrowers who had been on the same mortgage deal for the past five years 22 per cent cited the hassle of switching as the reason behind this while 15 per cent had not even thought about changing.
Which? Mortgage Advisers estimated borrowers with an average-priced home could pay up to £347 a month and more than £4000 per year more on a lender’s SVR, with this figure rising to £8700 per year in London.
David Blake, principal mortgage adviser at Which? Mortgage Advisers, said: "I would urge anyone with a mortgage to check what interest rate you are on and whether you’re paying more than you need to.
"The remortgage market is highly competitive at the moment, so there is a good chance that remortgaging will save you money. Speaking to an independent mortgage adviser is a great place to start to find out your options."