UK Mortgage Calculator

How a UK repayment mortgage works

With a repayment mortgage, each monthly payment covers some interest and pays off some of the amount you borrowed. If you keep up the payments for the full term, the loan is cleared at the end. This calculator uses the standard repayment formula:

Payment = L x r / (1 - (1 + r)^-n)

L is the amount borrowed, r is the monthly rate (the annual rate divided by 12) and n is the number of monthly payments. Enter the property price, your deposit, the rate and the term to see your monthly cost, total interest and loan to value (LTV).

Repayment or interest-only?

With an interest-only mortgage you pay just the interest each month and still owe the full loan at the end, so you need a separate plan to repay it. For a 200,000 loan, interest-only costs about 500 a month at 3%, 667 at 4% and 833 at 5%. Repayment costs more each month but clears the debt. Most home buyers use a repayment mortgage.

What a 200,000 mortgage costs over 25 years

Moving from 4% to 5% adds about 113 a month and roughly 34,000 in total interest. When your fixed deal ends, your new rate can make a large difference, so plan for it early.

Choosing the term

A longer term lowers the monthly payment but increases the interest you pay. At 3% on 200,000, a 20-year term costs about 1,109 a month, while a 30-year term costs about 843. The shorter term is dearer each month, yet it saves a great deal of interest overall. Try different terms in the calculator.

Understanding loan to value (LTV)

LTV is the share of the property price that you borrow. A 300,000 home with a 30,000 deposit means borrowing 270,000, or 90% LTV. Lenders usually offer better rates at lower LTVs, with improvements often at steps such as 90%, 85%, 75% and 60%. Many lenders accept a 5% deposit, but a bigger deposit generally gives you more choice and cheaper deals.

Fixed, tracker and variable rates

• Fixed rate: your rate stays the same for an initial period, often two or five years, so payments are predictable.
• Tracker rate: your rate follows a base rate, such as the Bank of England rate, plus a set margin, so payments can rise and fall.
• Standard variable rate: the lender can change it at any time. Many borrowers move onto this when a deal ends if they do not remortgage.

Costs beyond the monthly payment

The figure in the calculator does not include the other costs of buying. These can include stamp duty (Stamp Duty Land Tax in England and Northern Ireland, Land and Buildings Transaction Tax in Scotland and Land Transaction Tax in Wales), legal fees, surveys, valuation and arrangement fees, buildings insurance and moving costs. Check current rules on GOV.UK before you budget.

How much can you borrow?

Lenders often offer around four to four and a half times your income, sometimes more, and they test whether you could afford higher rates. They also look at your spending, debts and credit record. Use the UK mortgage affordability calculator for a first estimate.

Save interest by overpaying

Paying extra each month cuts the balance faster, which saves interest and shortens the term. Many fixed deals cap penalty-free overpayments, often at 10% of the balance each year. Check how much you could save with the mortgage overpayment calculator, and compare your income with your commitments using the debt-to-income calculator.

This calculator gives estimates for information only and is not mortgage advice. Speak to an FCA-authorised mortgage adviser before you borrow, as your home may be repossessed if you do not keep up repayments on your mortgage.

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Last updated October 2026. For information only, not financial advice.