Mortgage Repayment Calculator
Enter your mortgage amount, interest rate and term to see the monthly repayment, the total interest over the life of the loan and what you'll repay in total.
Last updated 4 July 2026 · Written and reviewed by Mustafa Bilgic
Mortgage repayment calculator
Monthly cost of a repayment mortgage.
Estimate on a fixed rate. Real deals change rate after the fixed period. Check with your lender.
How mortgage repayments are calculated
A repayment (capital and interest) mortgage is worked out so that equal monthly payments clear the loan exactly over the term. Early on, most of each payment is interest; as the balance falls, more goes to capital. The monthly figure depends on three things — the amount borrowed, the interest rate and the term — using the standard amortisation formula. This calculator applies that formula and also shows the total interest and total you'll repay.
A £220,000 mortgage at 4.5% over 25 years costs about £1,223 a month. Over the full term you'd repay roughly £366,900 — around £146,900 of interest on top of the amount borrowed.
Rate, term and total interest
Small changes matter enormously over 25 years. Dropping the rate from 4.5% to 3.5% on that £220,000 loan saves around £125 a month and over £37,000 in total interest. Extending the term lowers the monthly payment but increases total interest, because you're borrowing for longer. That's the trade-off to weigh — affordability now versus cost over time.
| Term | Monthly (£220k @ 4.5%) | Total interest |
|---|---|---|
| 20 years | £1,392 | £113,900 |
| 25 years | £1,223 | £146,900 |
| 30 years | £1,115 | £181,300 |
| 35 years | £1,041 | £217,300 |
Illustrative, fixed rate for the whole term.
Fixed periods and the SVR
Most UK mortgages fix the rate for two, five or ten years, then revert to the lender's standard variable rate (SVR), which is usually much higher. In practice you remortgage before that happens to secure a new deal. This calculator assumes one rate for the whole term, so treat it as the cost if your current rate continued — then plan to switch. Our remortgage calculator compares your current deal with a new one.
Overpaying to clear it sooner
Because interest is charged on the outstanding balance, overpayments are powerful: every extra pound reduces the balance immediately and saves all the future interest on it. Even £100 a month can knock years off a typical mortgage. Most lenders allow overpayments of up to 10% of the balance a year without penalty during a fixed deal — our mortgage overpayment calculator shows exactly how much time and interest you'd save.
Before you borrow
Lenders decide how much you can borrow from your income, outgoings and deposit, typically capping the loan at around 4.5 times income and stress-testing your ability to pay if rates rise. Work out your realistic budget first with our mortgage affordability calculator, and remember to factor in the stamp duty, valuation and legal costs on top of the deposit. Always get a personalised illustration from a lender or broker before committing.
Frequently asked questions
How much is the monthly payment on a £200,000 mortgage?
At 4.5% over 25 years, a £200,000 repayment mortgage costs about £1,112 a month. The exact figure depends on the interest rate and term — a lower rate or shorter term changes it significantly. Enter your own numbers above for a precise result.
What's the difference between repayment and interest-only?
On a repayment mortgage, each monthly payment covers interest and part of the capital, so the loan is cleared by the end of the term. On interest-only, you pay just the interest and the full balance remains due at the end — cheaper monthly but you must repay the capital separately.
Does a longer mortgage term cost more?
Yes. A longer term lowers the monthly payment but increases the total interest because you're borrowing for longer. Extending a £220,000 mortgage at 4.5% from 25 to 35 years cuts the monthly payment by around £180 but adds over £70,000 in total interest.
What happens when my fixed rate ends?
Your mortgage usually moves to the lender's standard variable rate, which is typically higher, unless you remortgage to a new deal first. Most people switch before the fixed period ends to avoid the jump in payments. Our remortgage calculator shows the potential saving.
Can I reduce my mortgage faster?
Yes, by overpaying. Because interest is charged on the outstanding balance, overpayments immediately reduce it and save future interest. Most lenders allow up to 10% overpayment a year penalty-free during a fixed deal. Even modest regular overpayments can shorten the term by years.