UK mortgage calculators
Mortgage Rate Shock Report
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Your estimate will appear here.
What this result means
This report compares two repayment illustrations with the same balance and term, then subtracts each payment and the costs you entered from net monthly income. It is a personal budgeting scenario, not a lender affordability test.
How to use the calculator well
- Use the balance and term from a current statement.
- Enter net income and essential commitments conservatively without double-counting the mortgage.
- Choose a scenario rate to explore, not a prediction, and repeat with other plausible cases.
Worked scenario
On a £200,000 balance over 25 years, compare 4% with 7%, then examine the monthly change and the remaining amount after the entered essential costs. A negative remainder is a prompt for early human action, not a product recommendation.
Questions people ask
Does a positive remainder mean the mortgage is affordable?
No. The tool cannot capture irregular costs, dependants, future changes, credit commitments or a lender's assessment.
What if the higher-rate scenario is difficult?
The FCA advises borrowers worried about payments to contact their lender as soon as possible. A regulated adviser or MoneyHelper can also provide appropriate support.
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.