UK Mortgage Repayment Calculator
Work out what a mortgage really costs: your monthly payment, the total interest over the term, and a year-by-year schedule showing how the balance falls. Switch between repayment and interest-only to compare.
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Loan-to-value: 87.7%
Amortisation schedule
| Year | Paid | Interest | Principal | Balance |
|---|---|---|---|---|
| 1 | £16,675 | £11,137 | £5,538 | £244,462 |
| 2 | £16,675 | £10,882 | £5,793 | £238,669 |
| 3 | £16,675 | £10,616 | £6,059 | £232,610 |
| 4 | £16,675 | £10,338 | £6,337 | £226,273 |
| 5 | £16,675 | £10,047 | £6,628 | £219,645 |
| 6 | £16,675 | £9,742 | £6,933 | £212,712 |
| 7 | £16,675 | £9,424 | £7,251 | £205,461 |
| 8 | £16,675 | £9,091 | £7,584 | £197,876 |
| 9 | £16,675 | £8,742 | £7,933 | £189,944 |
| 10 | £16,675 | £8,378 | £8,297 | £181,646 |
How is the monthly payment worked out?
Repayment mortgages use the standard amortisation formula M = P · r(1+r)n / ((1+r)n − 1), where P is the amount borrowed, r the monthly interest rate (annual rate ÷ 12), and nthe total number of monthly payments. Each payment first covers that month's interest; the remainder reduces the balance, which is why early payments are mostly interest and later ones mostly principal.
Worked example
Buying a £285,000 home with a £35,000 deposit means borrowing £250,000. Over 25 years at 4.5%, the monthly payment is £1,389.58 and the total interest comes to £166,875 — about 67% of the amount borrowed.
Frequently asked questions
How is a UK mortgage payment calculated?
Repayment mortgages use the standard amortisation formula M = P × r(1+r)^n / ((1+r)^n − 1), where P is the amount borrowed, r the monthly interest rate, and n the number of monthly payments. For example, borrowing £250,000 over 25 years at 4.5% costs £1,389.58 a month.
What is the difference between repayment and interest-only?
With a repayment mortgage each payment covers interest plus some of the loan, so you owe nothing at the end of the term. With interest-only you pay just the interest each month — payments are lower, but the full loan is still owed at the end and you need a separate plan to repay it.
What is loan-to-value (LTV) and why does it matter?
LTV is the loan amount as a percentage of the property price. A £35,000 deposit on a £285,000 home is an 87.7% LTV. Lower LTV bands (90%, 85%, 75%, 60%) typically unlock cheaper rates, so a slightly bigger deposit can reduce your monthly payment twice over.
Does this calculator include product fees or stamp duty?
No — it shows the loan itself: monthly payment, interest, and balance over time. Arrangement fees, valuation fees, and stamp duty land tax are one-off costs on top, and fixed-rate deals will change your rate when the fix ends.