Calculate your monthly repayment, total interest and total cost for any mortgage.
How sensitive is your payment? See what 1 percentage point, a longer term or a larger deposit does to the monthly cost in the mortgage rate sensitivity analysis.
| Loan Amount | — |
| Interest Rate | — |
| Term | — |
| Repayment Type | — |
| Total Interest Cost | — |
| Year | Payment | Interest | Capital | Balance |
|---|
This calculator uses the standard mortgage amortisation formula to calculate your monthly repayment. Every month you pay both interest (charged on the outstanding balance) and capital (which reduces the loan). Because the balance falls over time, the interest portion of each payment gradually decreases while the capital portion increases.
The monthly payment M is calculated as: M = P × [r(1+r)ⁿ] ÷ [(1+r)ⁿ − 1], where P is the loan amount, r is the monthly interest rate (annual rate ÷ 12 ÷ 100), and n is the number of monthly payments (years × 12).
With a repayment mortgage, each payment reduces your outstanding balance. At the end of the term, the loan is fully repaid. This is the most common type in the UK. With an interest-only mortgage, your monthly payment covers only the interest — your balance stays the same and you must repay the full loan amount separately at the end of the term.
UK lenders typically offer 4–4.5× your gross annual income as a maximum loan. Some lenders go up to 5–5.5× for higher earners or lower loan-to-value ratios. All lenders also apply stress tests — checking you can still afford repayments if rates rise. Most require at least a 5% deposit, but a 15–25% deposit gives access to significantly better rates.
Making overpayments reduces your outstanding balance faster, cutting total interest significantly. Many lenders allow up to 10% of the outstanding balance per year without penalty. Even small regular overpayments can reduce a 25-year mortgage term by several years.
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Standard amortisation arithmetic, plus the official context that affects the rate you will actually be offered. Checked on 2 September 2026.
Official figures this calculator applies
UKCalc assumptions — not official figures
Loan-to-value drives pricing. Rates step down at 90%, 85%, 80%, 75% and 60% LTV. A small increase in deposit that crosses one of those bands can cut the rate materially — often more than shopping around at the same LTV.