About the UK Mortgage Calculator
This UK mortgage calculator shows the monthly payment on a repayment or interest-only mortgage in pounds. Enter the property price, your deposit, the interest rate and the term, and it works out the loan, the loan-to-value ratio lenders use to set rates, the total interest and the total you will repay. On a repayment mortgage you can add a monthly overpayment to see how many years sooner you could be mortgage-free and how much interest you would save. All the sums run in your browser.
Updated October 2026
How to use the UK Mortgage Calculator
- 1Enter the property price and your deposit.
- 2Enter the interest rate from the deal you are looking at.
- 3Enter the mortgage term in years.
- 4Choose repayment or interest only.
- 5Optionally add a monthly overpayment and read the savings.
Understanding your monthly payment
On a repayment mortgage each payment covers that month's interest and pays off some of the loan. Early payments are mostly interest; later ones are mostly capital. Lengthening the term lowers the payment but increases the total interest, often by tens of thousands of pounds.
Why LTV matters
Lenders price mortgages in LTV bands. Moving from 90% to 85% or from 75% to 60% can unlock a noticeably lower rate. Use the calculator to see how a bigger deposit changes both the LTV and the payment.
- 95% LTV: smallest deposits, highest rates
- 90% and 85% LTV: common for first-time buyers
- 75% LTV and below: much better rates
- 60% LTV: usually the best rates available
The power of overpaying
Every extra pound you pay reduces the balance that interest is charged on. Overpaying £200 a month on a £225,000 mortgage at 4.5% over 25 years clears it about five and a half years early and saves around £37,000 of interest. Even small regular overpayments add up, especially in the early years.
Planning for rate changes
Try your current rate, then a rate one or two points higher, to see what your payment could become when your fixed deal ends. If the higher payment would be a stretch, consider a longer fix, a bigger deposit, or overpaying while rates are lower to build a buffer.
Before you apply
Lenders look at your income, regular spending and credit history as well as the deposit. Many lend up to about four to four and a half times household income, and they stress-test whether you could still pay if rates rose. Running the numbers here first helps you set a realistic budget before you speak to a broker or lender.
Phone or computer
The calculator updates as you type, so you can compare deals quickly on a phone while house hunting. Nothing is saved. A mortgage is more than a monthly payment. Compare other markets with the Mortgage Calculator, see the effect of extra payments with the Mortgage Payoff Calculator, and check your loan against the property with the Loan to Value Calculator.
Features
- Repayment and interest-only mortgages
- Loan to value (LTV) shown
- Total interest and total repaid
- Overpayment savings and new term
- Pounds sterling throughout
- No sign-up, nothing stored
Frequently asked questions
How are UK mortgage repayments calculated?
With interest worked out monthly on the balance. A £225,000 repayment mortgage at 4.5% over 25 years costs about £1,250.62 a month.
What is loan to value?
The mortgage as a percentage of the property price. A £25,000 deposit on a £250,000 home gives a 90% LTV. Lenders usually offer lower rates at 75% and 60% LTV.
How does an interest-only mortgage work?
You pay only the interest each month, so payments are lower, but the whole loan is still owed at the end of the term. Lenders want to see a credible plan to repay it.
How much can I overpay?
Many fixed-rate deals allow up to 10% of the balance each year without an early repayment charge. Check your mortgage offer before overpaying more.
Does the calculator include stamp duty or fees?
No. Stamp duty, arrangement fees, valuation and legal costs are extra. Some fees can be added to the loan, which increases the interest you pay.
Will my rate stay the same?
Usually not. Fixed rates last two to five years, after which you can remortgage. The calculator assumes one rate for the whole term to show the overall cost.