Mortgage lenders have passed on less than a third of the historically low base rate to customers, according to research conducted by price comparison site moneysupermarket.com.
The Bank of England has cut the base rate from 5% last August to the current rate of 0.5% - the lowest in the Bank's history - but the average mortgage rate has fallen just 1.3%.
The typical rate charged on new mortgages now stands at 5.12% compared to 6.42% last year.
"This further illustrates the divorce between mortgage rates and the base rate," said Hannah Skenfield of the price comparison site.