The Mortgage Repayment Calculator works out your monthly mortgage payment for any UK residential mortgage, based on the loan amount, interest rate, mortgage term and repayment type you choose. It supports both capital & interest (repayment) mortgages, where every payment gradually reduces what you owe, and interest-only mortgages, where your monthly payment covers just the interest and the capital is repaid separately at the end of the term. Alongside your monthly payment, it shows the total interest you'll pay over the life of the mortgage, the total amount you'll repay overall, and a year-by-year breakdown of how your balance reduces over time. Use it to see how changing your rate, term or repayment type affects what you pay each month and in total — figures are for illustration only and don't replace a formal mortgage illustration from a lender or broker.
| Year | Interest Paid | Capital Repaid | Remaining Balance |
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You've selected a standard capital & interest mortgage. Each monthly payment covers both the interest due and a portion of the capital you borrowed, so your balance reduces every month and reaches zero at the end of the term.
Based on your loan amount, interest rate and term, the calculator uses the standard mortgage amortization formula to work out a fixed monthly payment, then builds a month-by-month schedule to show how much of each payment goes toward interest versus capital, summarised year by year below.
Your calculation summary shows that for a loan of £250,000 at 4.50% over 25 years, choosing Capital & Interest (Repayment), your monthly payment would be £1,389.58, with total interest of £166,874.36 paid over the full term, and a total amount repaid of £416,874.36.
This calculator provides an illustrative estimate only, based on a fixed interest rate held constant for the whole term. It doesn't account for rate changes, fees, early repayment charges, payment holidays or changes to your circumstances. Always get a personalised mortgage illustration from a lender or whole-of-market broker before making decisions.
A repayment mortgage — also called a capital & interest mortgage — is the most common type of mortgage in the UK. Every monthly payment you make is split into two parts: one part covers the interest charged on your outstanding balance that month, and the other part reduces the capital (the amount you originally borrowed). Over the full term, assuming you keep up every payment, your balance is paid down to exactly zero, and you own the property outright with no mortgage debt remaining.
Because the payment amount is fixed (for a given interest rate), the split between interest and capital changes every month: early in the mortgage, most of your payment goes on interest because your balance is at its highest, while later in the term, most of your payment goes toward capital because the balance — and therefore the interest charged on it — has fallen.
An interest-only mortgage works differently: your monthly payment covers only the interest due that month, and none of it reduces the capital. This makes the monthly payment significantly lower than an equivalent repayment mortgage — but at the end of the term, you still owe the full original loan amount, which must be repaid in one lump sum, typically from savings, an investment plan (such as an ISA or endowment policy), or by selling the property.
Interest-only mortgages are now much less common for standard residential purchases in the UK — lenders generally require proof of a credible repayment strategy for the capital before approving one — but they remain widely used for buy-to-let mortgages, where many landlords plan to repay the capital by selling the property or refinancing.
For a repayment mortgage, the fixed monthly payment is calculated using the standard mortgage amortization formula:
M = P × r × (1+r)n ÷ [(1+r)n − 1]
Where P is the amount borrowed, r is your monthly interest rate (your annual rate divided by 12 and by 100), and n is the total number of monthly payments (your term in years multiplied by 12). If your rate is exactly 0%, the formula simplifies to the loan amount divided evenly by the number of payments (M = P ÷ n). For an interest-only mortgage, the formula is much simpler: your monthly payment is just M = P × r, since no capital is being repaid.
Several factors influence the interest rate a lender offers you, including:
A fixed-rate mortgage keeps your interest rate — and therefore your monthly payment — the same for an agreed period, commonly 2, 3, 5 or 10 years, regardless of what happens to the Bank of England base rate. A tracker mortgage moves directly in line with the Bank of England base rate plus a fixed margin, so your payment can rise or fall during the deal period. A standard variable rate (SVR) is the rate set by your own lender that you move onto automatically once your initial deal ends — SVRs are usually considerably more expensive than deal rates, which is why most borrowers remortgage or switch deals before reverting to it.
Making extra payments on top of your required monthly amount reduces your outstanding capital balance faster, which in turn reduces the interest charged in every subsequent month — potentially saving you a substantial amount over the life of the mortgage and letting you clear the loan earlier than scheduled. Most lenders cap the amount you can overpay each year (commonly 10% of the balance) without triggering an early repayment charge. For a detailed look at how different overpayment amounts affect your term and total interest, use our dedicated Mortgage Overpayment Calculator.
An early repayment charge is a fee your lender can apply if you repay more than your allowed overpayment limit, switch deals, or clear your mortgage entirely while you're still tied into a fixed, tracker or discounted deal period. ERCs are usually calculated as a percentage of the amount repaid early, and often reduce the longer you've been in the deal (for example, 5% in year one, falling to 1% in year five, before disappearing once the deal ends). ERCs don't normally apply once you're on your lender's standard variable rate, since that's not a tied-in deal.
When your initial deal period ends, your mortgage automatically moves onto your lender's standard variable rate (SVR) unless you take action. Because SVRs are usually much higher, most borrowers arrange a new deal in advance — either remortgaging to a different lender, or taking a "product transfer" to a new deal with their existing lender — typically starting the process 3 to 6 months before their current deal expires, to lock in a new rate and avoid any time spent paying the SVR.
Choosing a longer mortgage term spreads your capital repayments over more years, which lowers your monthly payment — but because you're paying interest for longer, the total interest you pay over the life of the mortgage increases. Choosing a shorter term raises your monthly payment but reduces the total interest paid considerably, since the capital is cleared faster and less interest accrues overall. There's no universally "right" answer — it's a trade-off between monthly affordability now and total cost over time.
Take a £250,000 repayment mortgage at a 4.5% annual interest rate over a 25-year term. The monthly interest rate is 4.5% ÷ 12 = 0.375%, and the number of payments is 25 × 12 = 300. Applying the amortization formula gives a fixed monthly payment of approximately £1,389.58. Over 300 payments, that totals £416,874.36 repaid in full, of which £166,874.36 is interest and £250,000 is the original capital. If the same loan were taken as interest-only instead, the monthly payment would be just £250,000 × 0.375% = £937.50, but the full £250,000 capital would still be owed at the end of the 25 years, on top of the £281,250 in interest paid along the way (£937.50 × 300 months).
LTV is calculated as your mortgage (or desired loan) amount divided by the property's value, expressed as a percentage: LTV = (loan amount ÷ property value) × 100. For example, borrowing £180,000 against a £200,000 property gives an LTV of 90%. Lenders group products into LTV bands — commonly 95%, 90%, 85%, 75%, 60% and so on — and generally offer their most competitive rates to borrowers in the lowest LTV bands, since a larger deposit or more equity reduces the lender's risk if house prices fall.
Your monthly mortgage payment covers only the capital and/or interest on the loan itself, as calculated by this tool. It doesn't include other regular property costs you'll need to budget for separately, such as buildings insurance (often required as a condition of the mortgage), ground rent and service charges on leasehold properties, Council Tax, utility bills, and general maintenance and repairs. Some lenders offer to collect buildings insurance or a mortgage protection policy alongside your payment, but these are separate charges layered on top of the repayment calculated here.
Before approving a mortgage, UK lenders assess affordability — checking that you could still meet your payments if interest rates rose, using an "affordability stress test" rate higher than your actual deal rate. This is separate from working out your likely monthly payment, and determines how much a lender is willing to let you borrow in the first place. If you want to understand how much you might be able to borrow based on your income and outgoings, try our dedicated Mortgage Affordability Calculator.
This calculator is designed to answer one question clearly — "what will my monthly mortgage payment be?" — but it's often useful alongside our other mortgage and property tools: the Mortgage Overpayment Calculator to see how extra payments shorten your term and cut interest, the Mortgage Comparison Calculator to compare two or more deals side by side, the Remortgage Calculator when your current deal is ending, and the Buy-to-Let Mortgage Calculator if you're financing a rental property rather than your own home.
Explore more of our UK mortgage tools to plan your borrowing from every angle:
For independent, government-backed guidance on mortgage repayments and lender conduct rules, see: