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Mortgage repayment calculator
Free · runs in your browser · updated 2026-07-05
How to use the mortgage calculator
- Enter the loan amountThe amount you're borrowing — property price minus your deposit.
- Add rate and termUse the rate from your mortgage offer or a current deal.
- Compare resultsSee monthly repayment, total interest and the interest-only equivalent.
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Buy NowHow is a monthly mortgage repayment calculated?
Lenders use amortisation: each payment covers that month's interest plus some capital, calculated so the balance reaches zero at the end of the term. This calculator uses the same standard formula.
What happens if I extend my mortgage term?
A longer term lowers the monthly payment but increases total interest substantially. £200,000 at 4.5% costs £1,112/month over 25 years but £1,013/month over 30 years — with about £31,000 more interest overall.
What's the difference between repayment and interest-only?
Repayment clears the loan by the end of the term. Interest-only payments are lower, but you still owe the full loan amount at the end and need a plan to repay it.
Does this include product fees or insurance?
No — it shows the core loan repayment only. Arrangement fees, buildings insurance and any premiums are on top.
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