UK mortgage calculators
Overpay Mortgage or Save Calculator
Enter your figures
Your estimate will appear here.
What this result means
This illustration shows extra debt repaid and accumulated savings at the same selected horizon. It does not recommend a route. If the mortgage is repaid early, it does not reinvest the payments subsequently freed up, so it is not a full wealth comparison.
How to use the calculator well
- Use the actual mortgage rate and a savings rate you can reasonably obtain after tax.
- Choose a comparison period that matches the mortgage deal or savings decision.
- Consider access to cash, tax, risk and early repayment limits alongside the mathematical result.
Worked scenario
With a 5% mortgage, a 4% savings rate and £200 a month for five years, the mortgage route may have a mathematical advantage before tax. Savings remain accessible, however, while mortgage overpayments generally do not.
Questions people ask
Does the calculator include savings tax?
No. Enter an after-tax savings rate if tax is relevant to you.
Does a higher savings rate always mean save?
No. Rates can change, investments can fall, and liquidity and personal risk tolerance matter.
Sources and review standard
Calculations are independently implemented illustrations and were reviewed on 4 September 2026. We check factual boundaries against MoneyHelper's mortgage cost guidance, FCA consumer mortgage information and relevant lender documentation. Rates and product terms are never presented as live offers.
Before relying on this estimate
This is an educational illustration, not mortgage, financial, tax or legal advice, a lender decision or an offer. Exact rates, fees, early-repayment charges and product rules can materially change the result.
Check the figures with your lender, broker or qualified adviser. Your home may be repossessed if you do not keep up repayments on your mortgage.
Editorial responsibility
Published by Acerville Sparks Limited. Software assists research, drafting and automated formula testing. Primary sources, assumptions and limitations are shown so readers can inspect the work. No independent mortgage professional or financial adviser review is claimed. Reviewed 4 September 2026.