Mortgage Calculator UK: Monthly Payment and LTV
Calculate your UK mortgage payment on a repayment or interest-only basis, see your LTV and total interest, and test what a rate rise would cost you.
A better-informed decision.
Complete the form to see your breakdown.
Method: standard amortisation formula, monthly rate = annual rate ÷ 12.
This mortgage calculator works out the monthly payment on a UK home loan from five inputs: property price, deposit, annual interest rate, term in years, and repayment type. For example, a £250,000 home with a £50,000 deposit at 5% over 25 years costs £1,169.18 a month on a repayment mortgage. If the rate rose by 3 points, the payment would be £1,543.63.
Repayment or interest-only?
- Repayment: each payment covers interest plus part of the loan. By the end of the term the loan is cleared.
- Interest-only: you pay only the interest, and the full loan is still owed at the end. Under FCA rules (MCOB 11.6.41), a lender may only offer this if you have a clear, credible plan to repay the loan.
Loan to value (LTV)
LTV is the loan divided by the property price. A £200,000 loan on a £250,000 home is 80% LTV, meaning a 20% deposit. Lower LTV means less interest in total and often more deals to choose from.
How the monthly figure is calculated
The calculator uses the standard amortisation formula at one fixed rate. The loan is price minus deposit. The monthly rate is the annual rate divided by 12, so 5% becomes about 0.4167%. The number of payments is the term times 12, so 25 years is 300 payments. The payment is the loan times the monthly rate, divided by one minus (one plus the monthly rate) raised to the power of minus the number of payments. For interest-only, the payment is simply the loan times the monthly rate.
Worked example: a £250,000 home
The 5% rate is illustrative, not a market rate.
| Item | Amount |
|---|---|
| Loan (£250,000 minus £50,000) | £200,000 |
| LTV | 80% |
| Monthly payment, repayment, 25 years | £1,169.18 |
| Total interest over 25 years | £150,754.02 |
| Total repaid | £350,754.02 |
| Payment at 8% | £1,543.63 (£374.45 more) |
| Monthly payment, interest-only | £833.33 |
| Total interest, interest-only, 25 years | £250,000, with £200,000 still owed |
From the same calculator: stretching the term to 30 years lowers the payment to £1,073.64 but raises total interest to £186,511.57. Cutting the deposit to £25,000 (90% LTV) raises the payment to £1,315.33.
The stress test
The calculator adds a line showing your payment at the entered rate plus 3 points. It shows your headroom; it is not a lender’s test.
What the FCA actually requires (MCOB 11.6.18): lenders must consider likely interest rates over at least the first five years, unless the rate is fixed for five years or more. They must have regard to market expectations and any Financial Policy Committee recommendation, and they must assume a rise of at least 1 percentage point even if rates are expected to fall.
What affects approval
MCOB 11.6 requires lenders to assess affordability from your income and spending. A lender may cap borrowing at a multiple of income, but must still show the loan is affordable. Committed spending such as loans, credit cards, hire purchase and child maintenance is counted. Newcomers should also expect questions on UK credit history, visa and the source of the deposit.
Islamic home purchase plans (Ijara and diminishing Musharaka) are regulated by the FCA when they meet the conditions in its guidance (Murabaha is usually treated as a regulated mortgage), and the same affordability rules apply. This calculator does not model their payments, so ask the provider for a written illustration of the total cost.
What the calculator does not cover
- Product, broker and valuation fees, legal costs and insurance.
- Rate changes after a fixed deal ends, early repayment charges and overpayments.
- Stamp duty. Use the stamp duty calculator.
- Whether anyone will lend to you. It calculates payments, not eligibility.
This is not financial advice, and we do not recommend lenders or products. Check any broker or lender on the FCA register ↗.
Frequently asked questions
Is this the payment I will actually make?
It is an estimate at one fixed rate for the whole term. If your deal fixes the rate for a set period only, the payment will change when that period ends.
Will a lender test me at plus 3 points?
Not necessarily. The rule is at least 1 point, based on market expectations.
How big a deposit do I need?
There is no single official figure. Each lender sets its own maximum LTV. Try different deposits in the calculator to see the effect.
Is interest-only cheaper?
Monthly, yes. Overall, no: in the example you pay £250,000 in interest and still owe £200,000.
Sources
Next step
Start with your take-home pay in the salary calculator, then add the payment and council tax to your cost of living budget using the council finder. New to the UK? Start with the first month guide. When you start viewing, use the housing checklist and the estate agents directory.
Reviewed 24 September 2026.