Mortgage Calculator
Use this mortgage calculator to find your monthly payment, loan-to-value and total interest from the price, deposit, rate and term.
Formula & worked example
Formula: Payment = L × r ÷ (1 − (1 + r)^−n), with r = annual rate ÷ 12 and n = years × 12. Loan-to-value = loan ÷ price.
Example: 350,000 price, 15% deposit, 4.5% over 30 years: loan 297,500, payment about 1,507.39, total interest about 245,160.
Method & source: Standard fixed-rate repayment (amortisation) formula. See how we test our calculators.
Next step: try loan repayments with extra payments or UK take-home pay.
What Is a Mortgage Calculator?
A mortgage calculator estimates the regular payment on a home loan from the property price, your deposit, the interest rate and the length of the mortgage. It also shows how much interest you will pay in total and how quickly the balance falls.
This mortgage calculator for your monthly payment uses a standard repayment (capital and interest) mortgage, offers UK and US wording, and lets you add running costs such as insurance so you can see the full monthly picture.
How Our Mortgage Calculator Works
Enter the price, your deposit or down payment as an amount or a percentage, the rate and the term.
- Loan amount: property price minus deposit, with the loan-to-value percentage shown.
- Monthly payment: the fixed instalment that repays the loan exactly over the term.
- Total interest: the extra you pay on top of the amount borrowed over the whole term.
- Rate check: a small table shows the payment if the rate is 1% lower, 1% higher or 2% higher.
- Yearly table and chart: interest paid, capital repaid and remaining balance for every year.
The payment shown is for capital and interest. Fees, taxes and rate changes after an initial fixed period are not included, so treat the result as a planning estimate.
Why Calculating Your Mortgage Matters
A mortgage is usually the largest debt you will take on. A few minutes of maths before you commit can save thousands.
- Find out what monthly payment fits your budget before house-hunting.
- See how a bigger deposit lowers both the payment and the total interest.
- Compare a shorter term with a longer one and the interest each costs.
- Stress-test your budget against higher interest rates.
- Understand how slowly the balance falls in the early years.
Use a mortgage calculator early, then confirm figures with a lender or independent adviser before you make an offer.
Worked walkthrough: a 350,000 home
Suppose a property costs 350,000 and you put down 15% (52,500). The loan is 297,500, an 85% loan-to-value. At 4.5% over 30 years the monthly payment is about 1,507.39, and total interest over the term is roughly 245,160, so you repay about 542,660 in all. The rate table shows how sensitive this is: at 5.5% the payment rises to about 1,689.17, and at 3.5% it falls to about 1,335.91. The yearly table shows that in year one most of each payment is interest, with the capital share growing each year.
Practical tips for mortgage calculations
- Do not stretch your budget to the maximum payment: leave room for maintenance, insurance and a rise in the interest rate.
- Compare a longer term with a shorter one. The longer term lowers the payment but usually costs far more interest overall.
- A larger deposit often reduces the interest rate you are offered as well as the amount borrowed – try 5%, 10% and 20% to see the effect.
- Check whether your lender allows overpayments and whether there is an early-repayment charge before assuming you can pay the loan off early.
- Remember the rate may change after an initial fixed or introductory period. Use the rate table to test a higher rate.
Frequently Asked Questions (FAQs)
With the amortisation formula: payment = loan × r ÷ (1 − (1 + r)^−n), where r is the monthly interest rate and n is the number of monthly payments. The calculator does this for you.
Requirements vary by lender and country, and a larger deposit usually unlocks better rates. Try different percentages to see how the payment and loan-to-value change.
LTV is the loan as a percentage of the property price. Borrowing £240,000 against a £300,000 property is an 80% LTV. Lower LTVs often qualify for lower interest rates.
No. It assumes a repayment mortgage, where every payment covers interest and reduces the loan. Interest-only payments would be just the balance × the monthly rate.
Interest is charged on the outstanding balance every month, so over 25 or 30 years it can approach or exceed the amount borrowed. A shorter term or an overpayment reduces it.
Estimates only – not financial advice. Results assume a fixed rate for the whole term and a repayment (capital and interest) mortgage, with no fees, taxes or rate changes. Lenders’ offers and affordability rules differ. Speak to a lender or independent mortgage adviser before you borrow. See our full disclaimer.