Mortgage Repayment Calculator
Calculate your monthly payment, total interest and full cost of any UK mortgage.
Monthly Payment
Loan to Value
Total Interest
Total Repaid
Specialist Mortgage Calculators
Need a more specific calculation? Use one of the specialist tools below.
Key Facts
- Primary keyword: mortgage calculator - 2,900 monthly searches
- Independent editorial guide - no affiliate links, no commission
- Sources: FCA, Bank of England, gov.uk, HMRC, Money and Pensions Service
- Last reviewed June 2026
What Is a Mortgage Calculator?
A mortgage calculator is a tool that estimates monthly mortgage payments based on the loan amount, interest rate, and term. A UK mortgage calculator helps buyers and homeowners understand what a mortgage will cost before applying, enabling informed decisions about property price, deposit size, and mortgage term.
Mortgage calculators are available from lenders, comparison websites, and independent financial guidance sites. The inputs required are: the loan amount (purchase price minus deposit), the interest rate, and the repayment term in years. The mortgage calculator applies the standard mortgage payment formula to produce a monthly payment figure.
A mortgage calculator is a starting point, not a lending decision. The monthly payment shown by a mortgage calculator assumes a constant interest rate for the full term, which does not reflect reality for most borrowers who remortgage every two to five years. A mortgage calculator result should be interpreted as an indicative figure rather than a precise prediction of actual costs.
How to Use a Mortgage Calculator UK
Using a mortgage calculator UK effectively requires accurate inputs. The loan amount is the purchase price minus the deposit - not the full property price. On a 300,000 pound property with a 60,000 pound deposit, the mortgage calculator input is 240,000 pounds, not 300,000 pounds.
The interest rate to use in a mortgage calculator UK should reflect the rate available to you at your expected LTV, not necessarily the headline rate advertised. Using a rate that is 0.5 to 1 percent above the current market rate provides a useful stress test of affordability if rates were to rise after the initial fixed period.
The repayment term significantly affects the mortgage calculator output. A 200,000 pound mortgage at 4.5 percent over 25 years gives a monthly payment of approximately 1,111 pounds. The same mortgage over 30 years gives approximately 1,013 pounds per month - 98 pounds less per month but 15,000 pounds more in total interest. A mortgage calculator makes this trade-off explicit and helps borrowers choose the term that best fits their circumstances.
Mortgage Calculator: Repayment vs Interest Only
A mortgage calculator for a repayment mortgage shows a monthly payment that includes both interest and capital repayment. Over the term, the outstanding balance reduces to zero. A mortgage calculator for an interest-only mortgage shows only the interest component - the capital balance remains unchanged throughout.
Repayment mortgage calculator: on a 200,000 pound loan at 4.5 percent over 25 years, the monthly payment is approximately 1,111 pounds. The total repaid is approximately 333,000 pounds - 133,000 pounds in total interest. The mortgage calculator shows this total cost alongside the monthly figure.
Interest-only mortgage calculator: the same 200,000 pound loan at 4.5 percent gives a monthly interest payment of 750 pounds. However, the 200,000 pound capital balance is not reduced and must be repaid at the end of the term. The total cost over 25 years is 225,000 pounds in interest plus 200,000 pounds capital - 425,000 pounds in total. A mortgage calculator that shows only the monthly interest payment without highlighting the capital repayment obligation can be misleading.
Mortgage Affordability Calculator
A mortgage affordability calculator estimates the maximum you can borrow based on income and outgoings. This is distinct from a monthly payment mortgage calculator - it approaches the calculation from the other direction, starting with income and working back to the maximum loan rather than starting with a loan amount and calculating the payment.
Most lenders use a multiple of 4 to 4.5 times gross annual income as the standard maximum, subject to a stress-tested affordability assessment. A mortgage affordability calculator based on an income multiple gives a quick indicative maximum. For example, a gross income of 60,000 pounds gives a mortgage affordability calculator result of 240,000 to 270,000 pounds at a 4 to 4.5 times multiple.
A mortgage affordability calculator that also includes committed monthly outgoings - loan repayments, credit cards, child maintenance - produces a more accurate result than one based on income alone. The lender's actual affordability assessment is income minus committed outgoings minus living costs, stress-tested at a rate above the product rate. The online mortgage affordability calculator is a useful planning tool but the lender's full assessment may differ.
Buy to Let Mortgage Calculator
A buy to let mortgage calculator assesses rental yield, loan affordability, and rental coverage ratio rather than personal income. The key calculation in a buy to let mortgage calculator is whether the expected rental income covers the mortgage interest at the lender's stress test rate - typically at 125 to 145 percent coverage.
A buy to let mortgage calculator for a 250,000 pound property with a 62,500 pound deposit (75 percent LTV mortgage of 187,500 pounds) at 5 percent interest: the monthly interest payment is 781 pounds. At a 125 percent coverage requirement, the minimum monthly rent to satisfy lenders is 976 pounds. The buy to let mortgage calculator confirms whether the expected market rent achieves this threshold.
The gross rental yield shown by a buy to let mortgage calculator is annual rent divided by property purchase price. A buy to let mortgage calculator that shows 1,100 pounds per month rent on a 250,000 pound property gives a gross yield of 5.28 percent. Most buy to let mortgage lenders require a minimum gross yield of 4 to 6 percent depending on their criteria.
Mortgage Overpayment Calculator
A mortgage overpayment calculator shows the financial benefit of paying more than the contracted monthly amount. By comparing two repayment schedules - standard and with overpayment - the mortgage overpayment calculator quantifies the interest saved and the term reduction from regular extra payments.
A mortgage overpayment calculator example: 200,000 pound mortgage at 4.5 percent over 20 years. Standard monthly payment: 1,265 pounds. Adding 200 pounds per month overpayment: the mortgage overpayment calculator shows a term reduction of approximately 3 years and 5 months, saving approximately 18,000 pounds in total interest.
The mortgage overpayment calculator is most useful for borrowers deciding whether to save or overpay the mortgage. When the mortgage interest rate exceeds the after-tax savings rate - which is almost always the case at current mortgage rates versus savings account rates - the mortgage overpayment calculator will show that overpaying beats saving from a pure financial return perspective.
Stamp Duty Calculator
A stamp duty calculator is used alongside a mortgage calculator to show the total upfront cost of a property purchase. The stamp duty calculator and the mortgage calculator address different parts of the property buying equation - the mortgage calculator shows the ongoing monthly cost, while the stamp duty calculator shows the one-off tax payable at completion.
For a 300,000 pound property in England, a stamp duty calculator gives: 0 percent on 250,000 pounds (nil) plus 5 percent on 50,000 pounds (2,500 pounds) for a standard buyer. A first time buyer stamp duty calculator shows nil on the full 300,000 pounds, saving 2,500 pounds under the first time buyer relief.
Using a mortgage calculator and a stamp duty calculator together gives a complete picture of both the upfront costs and the ongoing monthly costs of a property purchase. This combined view is essential for accurate financial planning - knowing the monthly mortgage payment is only useful if you also know whether you have sufficient cash to complete the purchase.
How Accurate Are Mortgage Calculators?
Mortgage calculator results are indicative rather than guaranteed. The actual monthly payment offered by a lender depends on the specific product selected, the lender's own rate for the applicant's LTV and credit profile, and any product fees added to the loan. A mortgage calculator using the advertised headline rate may show a lower payment than the rate actually offered to a specific borrower.
Mortgage calculators also assume a constant interest rate throughout the term. In practice, most borrowers remortgage every two to five years as fixed rate deals expire, resetting to a new rate. The long-term total interest shown by a mortgage calculator is therefore a modelled figure rather than a prediction of actual total cost.
For planning purposes, using a mortgage calculator with a rate slightly above the current market rate provides a useful buffer. Setting the mortgage calculator term to 25 years rather than 30 or 35 years gives a more conservative monthly payment estimate that is more likely to remain affordable if rates change. A mortgage broker can provide a more accurate estimate based on the specific products available to a given borrower.
Disclaimer: This guide is for informational purposes only and does not constitute financial advice. Products, eligibility criteria and regulations change frequently. Consult an FCA-authorised adviser before making any decision. Kael Tripton Ltd is not authorised or regulated by the Financial Conduct Authority.
Frequently Asked Questions
How does a mortgage calculator work?
A mortgage calculator applies the standard mortgage payment formula using the loan amount, interest rate, and term. It calculates the monthly payment required to repay the full loan including interest over the chosen term. The formula accounts for compound interest to produce an accurate monthly figure.
What is a good monthly mortgage payment in the UK?
A common guideline is that mortgage payments should not exceed 28 to 35 percent of gross monthly income. On a gross income of 50,000 pounds per year (4,167 pounds per month), a mortgage payment of 1,167 to 1,458 pounds is broadly within this range. The actual comfortable level depends on individual outgoings and lifestyle.
How much can I borrow on a mortgage calculator?
Most mortgage calculators use 4 to 4.5 times gross annual income as the standard borrowing multiple. On a 60,000 pound income, the mortgage calculator maximum is typically 240,000 to 270,000 pounds. Joint applications use combined income. The actual lender offer depends on the full affordability assessment.
What interest rate should I use in a mortgage calculator UK?
Use the current rate available at your expected LTV as a base. For stress testing, add 1 to 2 percent to model what the payment would be if rates rose after the fixed period. This gives a realistic picture of whether the mortgage remains affordable under different rate scenarios.
Is a mortgage calculator the same as an affordability calculator?
No. A mortgage calculator starts with a loan amount and calculates the monthly payment. A mortgage affordability calculator starts with income and calculates the maximum loan. They approach the same decision from different directions and are both useful planning tools.
Can a mortgage calculator tell me if I will be approved?
No. A mortgage calculator provides an indicative payment figure but cannot assess credit history, employment type, or the specific criteria of individual lenders. A mortgage in principle from a lender or assessment by a mortgage broker gives a more reliable indication of approval likelihood.
What is a buy to let mortgage calculator?
A buy to let mortgage calculator assesses rental yield, monthly interest payment, and whether the expected rent meets the lender's rental coverage requirement - typically 125 to 145 percent of the monthly interest at a stressed rate. It is used to assess the financial viability of a buy to let investment.
Sources
Last reviewed June 2026 · Kael Tripton Editorial
