UK Mortgage Repayment Calculator
Work out what a UK mortgage will actually cost you each month. The calculator below covers the three repayment structures lenders write today: capital and interest, interest only, and part-and-part. Enter your loan amount, rate and term, pick a structure, and see the monthly payment, total interest over the term and balance at the end.
UK mortgage repayment calculator
Calculator
Pick a repayment structure, enter your numbers, press Calculate. For part-and-part, set the share that is interest only.
Rates and lender criteria are subject to change. Figures correct at time of publication. Always speak to your broker for up-to-date rates and lending criteria on your specific case.
What this calculator tells you
The calculator solves a standard amortisation formula. For capital and interest, monthly payment is the figure that clears the loan to zero over the term you set. For interest only, monthly payment is the loan times the monthly rate, with the full balance still owed at the end. Part-and-part splits the loan into two slices: one slice repays on capital and interest, the other slice pays interest only and stays outstanding at the end.
For all three modes the output shows monthly payment, total paid across the term, total interest paid, and balance owed at the end of the term. The end balance is zero for capital and interest, the full original loan for interest only, and the interest-only slice for part-and-part.
Capital and interest, interest only, or part-and-part
Capital and interest
The default UK structure. Each monthly payment covers the interest charged for that month plus a slice of the original capital. Early in the term most of the payment is interest. By the final years most of the payment is capital. At the end of the term the balance is zero. This is what almost every residential mortgage looks like, particularly for first-time buyers, second-home purchasers and remortgages.
Interest only
Each monthly payment covers only the interest charged for that month. The capital does not reduce. At the end of the term the full original loan is still owed and must be repaid in a single lump sum from an agreed repayment vehicle: sale of the property, sale of other investments, bonus or carried-interest income, sale of a business, or maturing pension assets. Lenders require evidence of a credible repayment strategy at application and again at review. Common on high-net-worth lending, on RSU and bonus-led income profiles, and on buy-to-let where the rental yield comfortably covers interest.
Part-and-part
A mix. Part of the loan is on capital and interest and part is on interest only. Monthly cost is lower than full capital and interest but higher than full interest only. At the end of the term the interest-only slice is still owed and needs a repayment plan. Used where a borrower wants the discipline of paying down some capital but wants the monthly payment lower than a pure repayment structure allows.
Worked example: £400,000 loan at 4.75% over 25 years
| Structure | Monthly payment | Total interest | Balance at end |
|---|---|---|---|
| Capital and interest | £2,281 | £284,372 | £0 |
| Interest only | £1,583 | £475,000 | £400,000 |
| Part-and-part (50% IO) | £1,932 | £379,686 | £200,000 |
The interest-only payment is lower each month but the total cost of interest over the term is much higher because the balance never reduces. Part-and-part sits in the middle on both monthly and total cost. The right structure is the one that matches how you plan to repay the loan: regular income through the term, sale of the property at the end, sale of a separate asset, or a combination.
What we see most often on large loans is borrowers fixing on monthly cost without modelling the end balance. Interest only looks cheaper until you remember the full loan is still there at the end. Part-and-part is the structure we arrange most often for high-income clients who want the capital coming down at a manageable pace and the headroom to pay the interest-only slice off through bonus, RSU vesting or a property sale.
What the calculator can't show you
The calculator gives you the monthly cost on the loan itself. It does not show the lender's stress test, the affordability assessment, product fees, valuation costs, legal fees, broker fees or buildings insurance. It does not factor in early repayment charges if you want to overpay or refinance mid-term. It does not show what happens to your monthly payment if the rate changes part-way through the term, which it will on any product that is not a long-dated fix.
It is a planning tool. The real number you can borrow, and the rate you will be offered, come from a lender's full underwriting decision against your income, deposit, credit profile and the property itself. Speak to a broker before relying on any calculator output for an offer or a budget.
UK mortgage rates: 2026 context
The Bank of England base rate sits at 3.75% as of mid-2026. High-street residential mortgage rates broadly sit in the 4.0% to 5.5% range depending on LTV, fix length and product fees. Buy-to-let is typically 0.5% to 1.5% above residential equivalents. Private bank and specialist HNW rates can sit below the high street on strong AUM relationships. Specialist and adverse-credit lenders sit above. The right rate is the one that comes back from the lender that fits your case, not the headline best-buy tables.
Fox Davidson has full market access and arranges mortgages with named lenders including NatWest, Halifax, Santander, Barclays, HSBC, Nationwide, Skipton, TSB, Clydesdale, Coutts, Investec, Weatherbys and Barclays Private Bank. We approach the lender that fits the case at the rate and terms that work, rather than running every client through one panel.
Rates and lender criteria are subject to change. Figures correct at time of publication. Always speak to your broker for up-to-date rates and lending criteria on your specific case.
Frequently asked questions
What is the difference between capital and interest and interest only?
Capital and interest means each monthly payment covers the interest charged that month plus a slice of the original loan. At the end of the term the balance is zero. Interest only means each monthly payment covers only the interest. The capital does not reduce, and the full loan amount is still owed at the end of the term. Interest only is cheaper each month but more expensive in total interest, and you need a credible plan to repay the capital.
What affects my monthly mortgage cost?
Three things: the loan amount, the interest rate and the term. A larger loan, a higher rate or a shorter term all increase the monthly cost. Repayment structure matters too. Interest only is the cheapest monthly, capital and interest the most expensive, part-and-part in between. Product fees and any insurance the lender requires sit on top of the figure the calculator shows.
When does interest only suit a buyer?
Interest only suits borrowers with a clear repayment plan that is not regular income. Common cases: high earners with large bonus or RSU income, business owners with a planned sale or dividend distribution, HNW borrowers using investment portfolios or pension assets, and buy-to-let landlords where rental yield comfortably covers interest. Lenders require evidence of the repayment vehicle at application and ask for confirmation again during the term. It rarely suits a first-time buyer on standard PAYE income unless the lender's specific product allows it.
What mortgage term should I choose?
Longer terms reduce the monthly payment but increase the total interest you pay. Shorter terms are the opposite. The standard residential UK term is 25 to 30 years. Lenders will go to 35 or 40 years on younger applicants and on affordability stress. On a £400,000 loan at 4.75%, the difference between a 25-year and a 35-year term is roughly £400 per month, but the total interest paid jumps by around £130,000 over the life of the loan. We model both for clients before submitting an application.
How does a rate change affect my monthly cost?
On a fixed rate the monthly payment is locked for the fix period. When the fix ends the rate moves to the lender's standard variable rate or to a new product you switch to. On a £400,000 capital and interest loan over 25 years, every 1% movement in rate is roughly £225 per month. On a £1m loan it is roughly £560 per month. Stress-test your budget against a rate 1% to 2% above the rate you are quoted before committing.
What does the calculator not show?
It does not show the lender's affordability stress test, product fees, valuation fees, legal fees, broker fees, buildings insurance, life cover or any early repayment charges if you want to overpay or refinance mid-term. It does not show the rate the lender will actually offer you, which depends on full underwriting against your income, deposit, credit profile and the property. Treat the output as a planning figure, not an offer.
Can I overpay my mortgage?
Most UK mortgages allow overpayments of up to 10% of the outstanding balance per year without an early repayment charge. Above that limit, or if you settle the mortgage in full during a fix period, an early repayment charge applies, typically 1% to 5% of the amount repaid. Overpayments reduce the capital and the total interest paid. Check the product's terms before committing to a regular overpayment plan.