UK Mortgage Monthly Repayment Calculator
Estimate your monthly mortgage costs for the UK using property price, deposit, interest rate, and term. This is a guide only and not financial advice.
How this mortgage monthly repayment calculator UK works
This calculator estimates your monthly mortgage payment based on a standard UK setup: property value, deposit, annual interest rate, mortgage term, and repayment type. It then shows your projected loan amount, loan-to-value (LTV), monthly cost, total paid over the term, and total interest.
For repayment mortgages, the monthly amount includes both interest and principal, so your loan balance gradually falls. For interest-only mortgages, the monthly payment only covers interest and the original loan is still due at the end of the term.
Inputs used
- Property price: The purchase price of the home.
- Deposit: Cash you pay up front.
- Interest rate: Annual mortgage rate, entered as a percentage.
- Term: Mortgage length in years (commonly 20–35 years).
- Mortgage type: Repayment or interest-only.
The repayment formula (simplified)
For a repayment mortgage, the calculator uses the standard amortisation formula:
M = P × [r(1+r)^n] / [(1+r)^n - 1]
- M = monthly payment
- P = loan amount
- r = monthly interest rate (annual rate ÷ 12)
- n = total number of monthly payments
If the interest rate is 0%, the monthly payment is simply the loan amount divided by number of months.
Repayment vs interest-only in the UK
Repayment mortgage
With repayment, you clear both interest and capital over time. At the end of the mortgage term, the balance should be £0 if all payments are made as planned.
Interest-only mortgage
With interest-only, monthly payments are lower because you are not reducing the principal. You must have a credible repayment strategy in place to repay the full balance at term end. Many lenders apply stricter affordability and eligibility checks for this type.
What this calculator does not include
A monthly payment calculator is a strong starting point, but real-world ownership costs are broader. Consider adding:
- Arrangement/product fees from your lender
- Solicitor and conveyancing costs
- Survey/valuation fees
- Buildings insurance (and often contents insurance)
- Service charges/ground rent (for leasehold properties)
- Council tax, utilities, and maintenance
- Potential changes after fixed-rate periods end
How to reduce your monthly mortgage payment
- Increase your deposit: A bigger deposit lowers your loan and can unlock better rates.
- Improve your LTV band: Hitting common thresholds (for example 90%, 85%, 80%, 75%, 60%) may reduce rates.
- Extend the term: This lowers monthly payments but can increase total interest paid.
- Shop around and compare deals: Rates and fee structures vary significantly across products.
- Consider overpayments: Even modest overpayments can reduce long-term interest, subject to lender limits and ERC terms.
Example scenario
Suppose you buy a home for £300,000 with a £60,000 deposit. Your loan is £240,000 at 4.75% over 25 years on a repayment basis. The calculator estimates your monthly payment and projects total paid over the full term, helping you budget before speaking to a broker or lender.
You can then test alternatives quickly: increase deposit, adjust term, or compare repayment and interest-only outcomes.
Frequently asked questions
Is this calculator accurate for all lenders?
It gives a mathematically sound estimate, but each lender has different fees, affordability criteria, stress rates, and product structures. Final figures on your mortgage illustration may differ.
Can I use this for buy-to-let?
You can use it as a rough guide, but buy-to-let mortgages are usually assessed differently (including rental cover tests and often interest-only assumptions).
Does this include stamp duty?
No. Stamp duty (if applicable) is a separate upfront purchase cost and not part of your monthly repayment.
Should I choose the shortest term possible?
Not always. A shorter term reduces total interest but raises monthly costs. The best term is one that fits your cash flow, risk tolerance, and long-term plans.
Final thought
A good mortgage decision starts with clear numbers. Use this mortgage monthly repayment calculator UK to test realistic scenarios, then validate them with a whole-of-market broker or lender. Running multiple scenarios today can save you significant money and stress over the life of your mortgage.