Mortgage repayment calculator
See your monthly payment, the total interest you’ll pay, and how much overpaying could save — for a UK repayment mortgage. It all runs in your browser; nothing is sent anywhere.
Estimate for a capital-and-interest (repayment) mortgage. Real quotes vary with fees, rate changes and how interest is applied. Not financial advice.
Show the year-by-year breakdown
| Year | Interest paid | Capital paid | Balance left |
|---|
How your mortgage payment is worked out
A UK repayment (capital-and-interest) mortgage is calculated so that a fixed monthly payment clears the loan exactly by the end of the term. Each month, interest is charged on the balance still owed; whatever’s left of your payment reduces the capital. Because the balance is highest at the start, early payments are mostly interest and later ones are mostly capital — which is why overpaying early has the biggest effect.
Why overpaying saves so much
An overpayment comes straight off the capital, so from that month on you’re charged interest on a smaller balance — every month for the rest of the term. That compounds into a shorter term and less total interest. Most lenders let you overpay up to a set amount each year (often 10%) without an early repayment charge — check yours first.
Next steps
- See how a rate change hits your payments with the mortgage rate-change calculator.
- Read when to remortgage in the UK and what to do when a fixed deal ends.
Frequently asked questions
How is a monthly mortgage payment calculated?
A repayment mortgage uses the standard amortisation formula: your monthly payment is fixed so that the loan, plus interest charged each month on the outstanding balance, is cleared exactly by the end of the term. Early on, most of each payment is interest; later, most is capital.
Does overpaying a mortgage really help?
Yes. Overpayments come straight off the capital, so you pay interest on a smaller balance every month afterwards — which both shortens the term and cuts total interest. Check your lender’s annual overpayment limit (often 10%) to avoid early repayment charges.
Is this mortgage calculator accurate?
It uses the standard repayment formula and matches how UK lenders calculate capital-and-interest mortgages. Real quotes can differ slightly due to fees, the exact day interest is applied, and rate changes — always confirm figures with your lender.
Sources
- Mortgage calculator & repayment basics — MoneyHelper (Money & Pensions Service)
- Mortgages — Financial Conduct Authority (FCA)