Mortgage calculator

Enter the price of the home, pick a deposit and a term and set the rate you expect. The payment updates as you type, with the loan, the loan to value and what the mortgage costs over its life.

Typical deposit on a new build5% to 15%
Common term25 to 40 years
FormulaRepayment mortgage, fixed rate

Your figures

Deposit

How the payment is worked out

A repayment mortgage clears the loan and the interest in equal monthly instalments over the term.

The loan
The price less your deposit. A 10% deposit on £300,000 leaves a £270,000 loan at 90% loan to value.
The instalment
Loan × r ÷ (1 − (1 + r)^−n), where r is the monthly rate (the annual rate ÷ 12) and n the number of months. At 4.5% over 30 years, £270,000 costs about £1,368 a month.
What it assumes
One rate for the whole term. Most fixed deals last two to five years and then move to the lender’s variable rate, so the payment will change. Fees, insurance and any incentives from the developer are left out.
Source and rulesShowPageRule set 2026.1, last checked on 18 October 2026.The figures are illustrations from the inputs you give and the rules shown, not financial, tax or legal advice. Check them with a mortgage adviser or conveyancer before you rely on them. Your home may be repossessed if you do not keep up repayments on a mortgage secured on it.

Questions people ask

Why does a longer term cost more overall but less each month?

Spreading the loan over more months lowers each payment, but interest is charged on the balance for longer. On £270,000 at 4.5%, 25 years costs about £1,500 a month and £180,000 of interest; 35 years costs about £1,278 a month and £267,000 of interest.

Is a new-build mortgage different?

The arithmetic is the same. Lenders often cap apartments at 85% or 90% loan to value and hold a mortgage offer for six months, which matters if the home is not built yet; developers may also offer deposit contributions or part-exchange.

Which rate should I enter?

The rate on the deal you are likely to get, which depends on your deposit: 5% deposits pay more than 25% ones. Try a point higher as well to see what you could manage if rates rise when the fixed period ends.

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