Mortgage Calculator
Calculate principal-and-interest mortgage payments, total interest, deposit-based loan amount, and maximum borrowing from a monthly budget.
Mortgage Details
Enter your mortgage information.
Your Mortgage Breakdown
Monthly Payment
GBP 1,501.87
A GBP 300,000.00 mortgage at 3.5% over 25 years costs GBP 1,501.87 per month.
Total Payment
GBP 450,561.21
Total Interest
GBP 150,561.21
Balance Over Time
Amortisation Schedule (First 12 Months)
| Month | Payment | Principal | Interest | Balance |
|---|---|---|---|---|
| 1 | GBP 1,501.87 | GBP 626.87 | GBP 875.00 | GBP 299,373.13 |
| 2 | GBP 1,501.87 | GBP 628.70 | GBP 873.17 | GBP 298,744.43 |
| 3 | GBP 1,501.87 | GBP 630.53 | GBP 871.34 | GBP 298,113.90 |
| 4 | GBP 1,501.87 | GBP 632.37 | GBP 869.50 | GBP 297,481.53 |
| 5 | GBP 1,501.87 | GBP 634.22 | GBP 867.65 | GBP 296,847.31 |
| 6 | GBP 1,501.87 | GBP 636.07 | GBP 865.80 | GBP 296,211.24 |
| 7 | GBP 1,501.87 | GBP 637.92 | GBP 863.95 | GBP 295,573.32 |
| 8 | GBP 1,501.87 | GBP 639.78 | GBP 862.09 | GBP 294,933.54 |
| 9 | GBP 1,501.87 | GBP 641.65 | GBP 860.22 | GBP 294,291.89 |
| 10 | GBP 1,501.87 | GBP 643.52 | GBP 858.35 | GBP 293,648.37 |
| 11 | GBP 1,501.87 | GBP 645.40 | GBP 856.47 | GBP 293,002.98 |
| 12 | GBP 1,501.87 | GBP 647.28 | GBP 854.59 | GBP 292,355.70 |
About This Mortgage Calculator
This mortgage calculator estimates the principal-and-interest payment on a repayment mortgage. Enter a loan amount, annual interest rate, and term to see the monthly payment, total repayment, total interest, balance-over-time chart, and first 12 months of the amortisation schedule.
The With Deposit mode helps when you are comparing property prices and deposits: enter the property price and deposit amount, and the calculator works out the mortgage amount, deposit percentage, and monthly payment. The Affordability mode works backwards from a monthly payment budget to estimate the maximum mortgage balance supported by that budget.
Mortgage decisions are long-term, so the monthly payment is only one part of the picture. This calculator does not include stamp duty, property tax, insurance, PMI, service charges, broker fees, product fees, legal fees, or future rate changes. For a US mortgage payment with taxes and insurance calculator, use the mortgage PITI and escrow calculator. For UK ownership costs, use the UK mortgage total monthly cost calculator.
Mortgage Payment Example
Imagine a property costs GBP 300,000 and you have a GBP 45,000 deposit. The mortgage amount is GBP 255,000, which means an 85% loan-to-value mortgage.
At 5% interest over 25 years, the monthly repayment is roughly GBP 1,490. Over the full term, total repayments would be around GBP 447,000, meaning interest could be close to GBP 192,000 if the rate and term stayed unchanged.
This is why small rate differences matter. A lower rate, larger deposit, or shorter term can reduce the total interest significantly, even if the monthly payment change looks modest at first.
What Mortgage Affordability Really Means
Affordability is not just whether the mortgage payment fits. It is whether the payment still works after council tax or property tax, insurance, utilities, repairs, childcare, transport, food, savings, and unexpected costs. Those costs are outside this calculator; US buyers can use the mortgage PITI and escrow calculator, while UK buyers can use the UK mortgage total monthly cost calculator.
Stress testing is important. Try the calculator with a higher interest rate, a shorter term, or a reduced monthly budget. If the payment becomes uncomfortable quickly, the property budget may be too close to the edge.
Ways to Reduce Mortgage Cost
The main levers are deposit size, interest rate, term, and overpayments. A larger deposit may unlock a better loan-to-value band. A lower rate reduces interest immediately. A shorter term reduces total interest but raises the monthly payment.
Overpayments can be powerful because they reduce the balance that interest is charged on. Before overpaying, check whether your mortgage has annual limits or early repayment charges. Some borrowers prefer to keep cash in an emergency fund before making extra mortgage payments.
Reading the result with real-world context
Standard mode estimates the monthly repayment from a known mortgage balance, rate, and term.
With Deposit mode calculates the mortgage amount from property price minus deposit, then estimates the payment.
Affordability mode estimates the maximum mortgage balance supported by a monthly payment budget, rate, and term.
The result is principal and interest only. Taxes, insurance, service charges, stamp duty, PMI, escrow, and fees are outside the calculation; use mortgage PITI and escrow for the US tax, insurance, PMI, and escrow version, or UK mortgage total monthly cost for UK council tax, insurance, service charge, maintenance, and utilities.
Common mistakes to avoid
Treating the calculated mortgage payment as the full cost of owning a home.
Using Affordability mode as if it were lender approval rather than a payment formula.
Ignoring rate changes, product fees, legal costs, insurance, maintenance, property tax or council tax, and emergency savings.
How to combine this with related calculators
Use amortisation when you want payment frequency options, extra payment modelling, or longer schedule views.
Use debt to income when the question is whether housing and other debt payments are too high relative to income.
Use rent vs buy when the decision is whether buying beats renting after wider ownership costs.
Use mortgage PITI and escrow when the missing piece is a US mortgage payment with taxes, insurance, PMI, and estimated escrow.
Use UK mortgage total monthly cost when the missing piece is UK council tax, buildings insurance, service charge, ground rent, maintenance, utilities, and take-home pay pressure.
When to revisit the numbers
Rerun the payment when the rate, property price, deposit, term, or monthly budget changes.
Review again before a fixed rate ends, before making an offer, or when lender fees and product rates change.
Keep a separate list of housing costs outside the calculator so the mortgage payment does not crowd out maintenance, insurance, tax, and emergency savings.
How to Use This Calculator
- 1
Choose your calculation mode
Standard calculates the monthly payment on a known mortgage amount. With Deposit lets you enter the property price and deposit to calculate the loan amount. Affordability works backwards from your monthly payment budget to estimate the maximum mortgage balance.
- 2
Enter your mortgage details
Provide the loan amount (or property price and deposit), your expected annual interest rate, and the mortgage term in years. A standard UK residential mortgage runs 25 years, but terms from 10 to 40 years are available.
- 3
Review the cost breakdown
The results show your monthly payment, total amount repaid, and total interest over the full term. The balance-over-time chart shows how the outstanding mortgage shrinks year by year.
- 4
Read the amortisation schedule
The first 12 months breakdown shows exactly how each payment is split. In the early years, a large proportion goes to interest. This shifts over time as the balance reduces and more of each payment goes toward repaying the principal.
Frequently Asked Questions
How is the monthly mortgage payment calculated?
The monthly repayment is calculated using the standard amortisation formula: M = P × r(1+r)^n / ((1+r)^n − 1), where P is the loan amount, r is the monthly interest rate (annual rate ÷ 12), and n is the total number of monthly payments. This produces a fixed payment that covers accruing interest and gradually pays down the principal, so the loan is fully repaid at the end of the term.
What is included in the monthly payment?
This calculator shows principal and interest only - the repayment amount based on the mortgage balance, rate, and term. It does not include insurance, property tax or council tax, service charges, ground rent, PMI, escrow, maintenance, broker fees, legal fees, or lender product fees.
Should I choose a 15-year or 25-year mortgage?
A shorter term means higher monthly payments but significantly less interest paid overall. A 25-year term spreads the cost lower month-to-month but you pay much more in total. For example, a GBP 200,000 mortgage at 4% costs GBP 1,055/month over 25 years (total: GBP 316,500) but GBP 1,479/month over 15 years (total: GBP 266,220). If you can afford the higher payment, the shorter term is almost always the better long-term choice.
How does the interest rate affect my payment?
Even small changes in interest rate have a significant effect over a 25-year term. On a GBP 250,000 mortgage, moving from 3% to 5% raises the monthly payment by around GBP 280 and adds roughly GBP 84,000 in total interest. This is why remortgaging to a lower rate - even 0.5% lower - can save tens of thousands of pounds over the life of the loan.
Does this mortgage calculator include taxes or insurance?
No. It calculates principal-and-interest mortgage payments only. Taxes, insurance, escrow, PMI, stamp duty, lender fees, and legal costs need to be estimated separately before you decide what is affordable.
What is an amortisation schedule?
An amortisation schedule shows how each monthly payment is split between interest and principal repayment. In the early years, most of the payment goes toward interest because the outstanding balance is high. Over time, as the balance falls, more of each payment reduces the principal. The schedule below shows the first 12 months - the pattern continues until the loan is fully repaid.
Is the Mortgage Calculator financial advice?
No. It is a general planning estimate based on the values you enter. Confirm important borrowing, investing, tax, or property decisions with qualified professionals and official terms from lenders or providers.
How often should I update my inputs?
Update when rates, income, prices, rent, contributions, or goals change materially. For most household finance decisions, reviewing every few months or after a major change is enough.
Why might this differ from my bank or broker quote?
A broker quote may include product fees, valuation fees, exact payment dates, daily interest, introductory rates, insurance, taxes, or lender affordability rules. This calculator estimates principal-and-interest repayment from the values you enter.