Mortgage Calculator UK
Monthly mortgage repayments depend on how much you borrow, the rate and the term. On a £250,000 repayment mortgage at 4.5% over 25 years, payments are about £1,389 with £166,700 total interest. Over 30 years payments fall to £1,267 but interest rises to £206,200. Enter your details below.
Calculation method: Amortised loan repayment formula. This tool runs a model on the figures you enter, so there is no official rate table behind the result.
Calculator
The total amount you wish to borrow.
The interest rate on your mortgage deal. Check your offer letter or ask your broker.
Most UK mortgages run 25 to 30 years. Longer terms mean lower monthly payments but more total interest.
What this calculation assumes
Monthly payment is the standard annuity formula, P x (r(1+r)^n) / ((1+r)^n - 1), where r is the interest rate you enter divided by twelve and n is the term in months. Interest is charged on the reducing balance each month.
- The interest rate you enter is fixed for the whole term
- Payments are monthly, equal, and made on time
- Fees, insurance and any early repayment charge are excluded unless you enter them
- This is not a quote and no lender's actual pricing is used
Stay updated
Get UK Finance Tips Weekly
Tax changes, HMRC rate updates, and money-saving guides. No spam - unsubscribe any time.
How Mortgage Calculator UK Works
We use the standard amortisation formula to calculate your fixed monthly repayment. Each month, the interest charged reduces as your outstanding balance falls, so more of each payment goes toward capital over time. To see how much you could borrow before choosing a loan size, try our mortgage affordability calculator.
Repayment vs interest-only
Repayment mortgages guarantee the debt is cleared by the end of the term. Interest-only mortgages have lower monthly costs but require a separate repayment strategy (savings, investments, property sale). Most residential lenders require a repayment mortgage.
The amortisation chart
The chart shows your outstanding balance declining over the mortgage term alongside the annual split between interest and capital repaid each year.
Frequently Asked Questions
Monthly repayments are calculated using the standard amortisation formula: M = P × [r(1+r)^n] / [(1+r)^n - 1], where P = loan amount, r = monthly interest rate (annual rate / 12), and n = total number of monthly payments. The result is a fixed monthly payment that covers both interest and capital, with the interest portion decreasing over time.
With a repayment mortgage, each monthly payment covers the interest charged that month plus a portion of the capital. At the end of the term, the mortgage is fully paid off. With an interest-only mortgage, you only pay the interest each month - the full capital amount remains owed at the end of the term and must be repaid in one lump sum.
Most UK lenders will lend 4 to 4.5 times your gross annual income. Some lenders offer up to 5 to 5.5 times income for high earners or professionals. Joint applications use combined income. Stress testing means the amount you can borrow is also limited by your ability to afford repayments at a rate typically 3% above the reversion rate. Use our mortgage affordability calculator for a personalised estimate.
Mortgage rates in 2025 vary significantly by LTV, deal type, and lender. Two-year fixed rates typically range from 4 to 5.5% for 60 to 90% LTV. Five-year fixes tend to be priced similarly or slightly lower. Tracker and variable rates follow the Bank of England base rate. Use our LTV calculator to see which rate band you qualify for.
Related Calculators
View allRemortgage Calculator
Compare your current payment with a new deal after fees.
Mortgage Affordability Calculator
Estimate how much you can borrow at 4.5 times income.
Council Tax Calculator
Estimate council tax, a core running cost of owning a home.
Mortgage Overpayment Calculator
See interest saved by overpaying.
LTV Calculator
Calculate your loan-to-value ratio.
Stamp Duty Calculator
Calculate SDLT on your purchase.
Was this useful?
Sources and method
This calculator has no external rate table behind it. The result comes from the figures you enter and the model described in our methodology.
Method: Amortised loan repayment formula.
Spotted a figure that looks wrong? Report a correction and we will check it against the source above.
Further reading
Background references used while writing this page. The sources behind the calculated figures are listed above.
Disclaimer: This calculator provides estimates based on standard HMRC rates for 2026/27. Results may vary based on individual circumstances. This is not financial advice. Always consult a qualified accountant or CIMA-qualified financial adviser for personal tax matters.