UK Mortgage Repayment
Calculator

This calculator supports two types of UK mortgage: repayment and interest-only. With a repayment mortgage, every monthly payment chips away at both the interest and the original loan balance, so the debt is fully cleared by the end of the term. An interest-only mortgage charges you just the interest each month — meaning lower payments but the full loan amount still outstanding when the term ends. Most UK homebuyers choose repayment because it guarantees the property is owned outright at the end.

Monthly payments on a repayment mortgage are calculated using the standard amortisation formula: M = P [ r(1+r)^n ] / [ (1+r)^n - 1 ], where P is the loan principal, r is the monthly interest rate (annual rate divided by 12) and n is the total number of monthly payments. This formula ensures each payment is identical throughout the term, but the proportion going toward interest versus principal shifts over time. In the early years, the majority of each payment covers interest. As your balance shrinks, more of each payment goes toward reducing the actual debt.

Even small changes to your interest rate can have a significant impact on what you pay each month and over the lifetime of the mortgage. For example, on a £250,000 mortgage over 25 years, increasing the rate from 4% to 5% adds roughly £142 per month — that is an extra £42,600 over the full term. This is why shopping around for the best rate and reviewing your deal before it expires can save you tens of thousands of pounds.

Overpayments are one of the most powerful tools available to UK mortgage holders. By paying even a small amount extra each month, you reduce the outstanding balance faster, which means less interest accrues in future months. The effect compounds over time: a £100 monthly overpayment on a typical mortgage can shave years off the term and save thousands in interest. Most UK lenders allow you to overpay up to 10% of the outstanding balance per year without incurring early repayment charges — always check your mortgage terms first.

The calculator also shows your loan-to-value (LTV) ratio, which is the percentage of the property's value that you're borrowing. LTV is one of the most important factors lenders consider when pricing your mortgage. A lower LTV (meaning a bigger deposit) unlocks better rates and reduces the lender's risk. The amortisation schedule beneath the results lets you explore exactly how your balance, interest and principal payments evolve year by year across the full term.

Fixed vs variable rates. The UK mortgage market offers two broad categories: fixed-rate and variable-rate deals. A fixed-rate mortgage locks your interest rate for a set period — usually 2 or 5 years — giving you predictable, unchanging monthly payments regardless of what happens to the Bank of England base rate. Variable-rate mortgages (including trackers and standard variable rates) move with the market. Trackers follow the base rate plus a set margin, while SVRs are set by the lender and can change at any time. Fixed deals offer security; variable deals can be cheaper but carry the risk of rising payments.

Stress testing at 3% above. When you apply for a mortgage, lenders don't just check whether you can afford the payments at the product rate. They stress-test your application at a rate typically 3% above the deal you're applying for. This ensures you could still meet repayments if rates rise significantly. For example, if you apply for a mortgage at 4.5%, the lender will check affordability at 7.5%. This is why some borrowers find they can't borrow as much as they expected — use our mortgage affordability calculator to see what you might qualify for.

LTV bands and how they affect rates. Loan-to-value (LTV) is the single biggest factor in determining the rate you'll be offered. Lenders price mortgages in bands — typically 60%, 75%, 80%, 85%, 90% and 95% LTV. The lower your LTV, the better the rate. Moving from 90% LTV to 85% LTV, for example, can cut your rate by 0.3–0.5%, saving thousands over the term. If you're close to a band boundary, it may be worth increasing your deposit slightly to unlock the next tier. Our house deposit calculator can help you plan.

Arrangement fees. Many of the lowest-rate mortgage deals come with a product or arrangement fee, typically ranging from £500 to £2,000. You can usually choose to pay the fee upfront or add it to the mortgage balance. Adding it to the loan means you'll pay interest on the fee for the full term, which can make a seemingly cheap deal more expensive overall. Always compare the total cost of the mortgage (payments plus fees) rather than the headline rate alone.

Early repayment charges (ERCs). If you're on a fixed or discounted deal, repaying the mortgage early — whether by overpaying beyond the allowed limit, switching lender or selling the property — will usually trigger an early repayment charge. ERCs are typically 1–5% of the outstanding balance and decrease as you approach the end of the fixed period. Always check your ERC schedule before making large overpayments. Our mortgage overpayment calculator shows exactly how much you can save within your lender's limits.

Remortgaging. When your fixed or introductory deal ends, you'll typically revert to your lender's standard variable rate (SVR), which is almost always more expensive. Remortgaging — switching to a new deal, either with your current lender or a different one — can save you hundreds of pounds a month. You should start looking for a new deal 3–6 months before your current rate expires. Use our remortgage calculator to compare the cost of staying on your SVR versus switching, and our stamp duty calculator if you're considering moving rather than remortgaging. First-time buyers should also check our first-time buyer mortgage calculator for deals and relief specific to new buyers.

With a repayment mortgage (also called a capital and interest mortgage), each monthly payment covers both the interest charged that month and a portion of the original loan amount. By the end of the term, the entire debt is cleared. This is the most common type of residential mortgage in the UK and is what this calculator models by default.

With an interest-only mortgage, your monthly payments only cover the interest — you do not reduce the original loan balance at all. At the end of the term, you still owe the full amount borrowed and need a repayment strategy (savings, investments, or selling the property) to clear it. Monthly payments are significantly lower, but the total cost over the term is higher because you never reduce the principal.

For example, on a £250,000 mortgage at 4.5% over 25 years: the repayment option costs £1,390 per month and you pay £167,014 in total interest. The interest-only option costs just £938 per month — £452 less — but you still owe £250,000 at the end, and you pay £281,250 in total interest. Use our interest-only mortgage calculator to compare both options side by side.

Overpaying your mortgage — even by a small amount each month — reduces the outstanding balance faster, which means you pay less interest overall and clear the debt sooner. Most UK lenders allow you to overpay up to 10% of the outstanding balance per year without triggering early repayment charges.

The table below shows how different monthly overpayment amounts on a £250,000 repayment mortgage at 4.5% over 25 years affect the total interest paid and years saved.

Most UK lenders offer between 4 and 4.5 times your annual household income. Some specialist lenders — particularly for professionals like doctors, accountants and lawyers — stretch to 5 or even 5.5 times income. Joint applicants can combine their salaries.

The quick-reference table below shows typical maximum mortgage amounts based on income multiples. These are indicative — your actual borrowing will depend on outgoings, credit score, existing debts and the lender's stress test (typically calculated at 3% above the product rate).

If you are buying your first home, you may benefit from several schemes and reliefs designed specifically for first-time buyers in the UK:

Stamp duty relief. First-time buyers pay no stamp duty on the first £425,000 of the property price (for homes up to £625,000). This saves up to £6,250 compared to a standard purchase. Use our first-time buyer stamp duty calculator to see your exact saving.

Lifetime ISA (LISA). If you are aged 18–39, you can save up to £4,000 per year into a Lifetime ISA and receive a 25% government bonus (up to £1,000 per year). The maximum property price is £450,000. This can be a powerful way to boost your deposit.

Shared Ownership. You can buy a share of a property (typically 25–75%) and pay rent on the remainder. This reduces the deposit and mortgage required. Over time, you can "staircase" — buy additional shares until you own the property outright.

95% LTV mortgages. Several major lenders offer mortgages with just a 5% deposit for first-time buyers, though the interest rates are higher than deals at 85% or 90% LTV. On a £250,000 property, 5% is £12,500. Our house deposit calculator shows how long it will take to save, and our first-time buyer mortgage calculator estimates your monthly payments with FTB-specific rates.

Budget for extras. Beyond the deposit, budget for solicitor fees (£1,000–£2,000), survey costs (£300–£1,500), mortgage arrangement fees (£0–£2,000) and moving costs. Our conveyancing costs calculator and moving costs calculator can help you plan the full budget.