Calculate your monthly mortgage repayments, total interest paid and the overall cost of your mortgage. Adjust the property price, deposit, interest rate and term to compare different deals. Updated for 2026/27.
Enter the property price, your deposit amount, the annual interest rate and the mortgage term in years. The calculator will instantly show your monthly repayment, the total amount you will repay over the full term and how much of that is interest.
Your monthly mortgage payment is calculated using the formula: M = P[r(1+r)^n]/[(1+r)^n-1] where P is the loan amount, r is the monthly interest rate (annual rate ÷ 12) and n is the total number of monthly payments.
Average UK mortgage rates in 2024 range from around 4.5% to 6.5% depending on the loan-to-value ratio and fixed term length. A larger deposit typically secures a lower interest rate. Use this calculator to compare different rate scenarios.
While 5% deposit mortgages exist, they come with significantly higher interest rates and strict lending criteria. Most lenders offer their best rates to borrowers with 25-40% deposits. With a 5% deposit on a £300,000 property, you might pay 5.5-6% interest, whereas a 25% deposit could secure 4.5-5% — saving you hundreds monthly. First-time buyers should realistically aim for 10-15% minimum to access decent rates and avoid being stuck in negative equity if house prices fall. The Help to Buy ISA and Lifetime ISA schemes can boost your deposit with government bonuses of 25% on savings up to certain limits. Many buyers benefit from the Bank of Mum and Dad, with parents gifting or loaning deposit funds, though lenders will scrutinize gifted deposits to ensure they're genuine gifts not loans requiring repayment. Building a larger deposit takes longer but saves substantially over the mortgage term — the difference between 10% and 25% deposit on a £300,000 property could save you £50,000+ in interest over 25 years. Consider that renting while saving a bigger deposit might cost you £12,000 yearly but save you £2,000+ annually in mortgage interest plus give you access to better properties with accepted offers. Your deposit also affects loan-to-value ratios which determine available mortgage products — crossing thresholds like 90%, 85%, 75% LTV opens up significantly better rates and more lenders willing to offer mortgages.
This depends on your circumstances, risk tolerance, and interest rate expectations. Two-year fixes typically offer slightly lower rates than five-year fixes (currently around 0.2-0.4% difference) and provide flexibility to remortgage sooner if rates fall. They're suitable if you expect to move house within 2-3 years, anticipate salary increases allowing larger overpayments, or believe interest rates will fall significantly. However, you face remortgaging fees every two years (typically £1,000-2,000 for valuation and legal work) and the risk that rates rise substantially when you remortgage. Five-year fixes provide longer certainty on payments, which helps with budgeting and protects against rate rises. They're ideal if you value stability, expect rates to rise or stay high, plan to stay in the property long-term, or want to avoid the hassle of remortgaging frequently. The rate difference might be 0.3% higher (e.g., 5.0% vs 4.7% for a 2-year) but you save on remortgaging fees and gain peace of mind. Consider this: on a £250,000 mortgage, 5% for 5 years costs about £1,460 monthly versus 4.7% for 2 years at £1,430 monthly — only £30 difference. But if rates jump to 6% when your 2-year ends, your payment becomes £1,610 (£150 more than the 5-year fix). Most financial advisers currently lean toward 5-year fixes given economic uncertainty and historically high rates that could persist. Some borrowers split the difference with 3-year fixes for moderate stability without locking in too long.
Most mortgages allow overpayments of 10% of the outstanding balance annually without penalties, though this varies by lender. Overpaying reduces the term and total interest paid dramatically. Adding just £100 monthly to a £200,000 25-year mortgage at 5% saves roughly £30,000 in interest and clears the mortgage 5 years early. However, overpaying isn't always the smartest financial move. If your mortgage rate is 3.5% but you have credit card debt at 18%, pay the credit cards first. Similarly, if you have no emergency fund, build 3-6 months expenses in accessible savings before overpaying the mortgage — losing your job when you've overpaid £20,000 into your mortgage doesn't help if you can't access that money. Consider whether investing might return more than your mortgage rate: with a 4% mortgage, investing in a pension or ISA potentially returning 6-7% long-term could be more beneficial, plus pension contributions receive tax relief (effectively 25-45% boost). That said, guaranteed returns from paying down debt are attractive when investment returns are uncertain. Many people adopt a balanced approach: maximizing pension contributions to get employer match and tax relief, building emergency savings, then overpaying the mortgage with remaining surplus. The psychological benefit of mortgage-free living shouldn't be ignored either — while mathematically suboptimal, being debt-free often reduces stress and provides flexibility that's worth more than marginal investment returns. Some lenders allow overpayment holidays or offer offset mortgages where savings offset the mortgage balance for interest calculation while remaining accessible for emergencies — these provide the best of both worlds.
Monthly payment = £1,461. Total paid over 25 years = £438,300. Total interest = £188,300. This means you pay 75% more than you borrowed. Increasing payments to £1,600 monthly (£139 extra) clears the mortgage in 20 years saving £40,000 in interest. The first payment splits approximately £1,020 to interest and only £441 to principal, but by year 15 this reverses with more going to principal than interest.
With 5% deposit (£15,000): Borrowing £285,000 at 5.5% over 25 years = £1,754 monthly, total interest £241,200. With 25% deposit (£75,000): Borrowing £225,000 at 4.8% over 25 years = £1,299 monthly, total interest £164,700. The larger deposit saves £455 monthly and £76,500 total interest despite the longer time needed to save the extra £60,000 deposit. It also provides £60,000 equity buffer against house price falls.
£200,000 mortgage over 25 years. Option A: 2-year fix at 4.7% = £1,145 monthly for 2 years (£27,480 total). If rates rise to 5.5% after 2 years, £1,235 monthly for next 23 years (£340,860 total) = £368,340 grand total. Option B: 5-year fix at 5.0% = £1,169 monthly for 5 years (£70,140 total), then reverting to 5% for 20 years (£243,360) = £313,500 grand total. The 5-year fix saves £54,840 despite slightly higher initial rate, because it protected against the rate rise. This illustrates why certainty can be valuable.
Get a mortgage in principle before house hunting — it shows sellers you're a serious buyer and speeds up the purchase process once you find a property. Shop around extensively as rates vary significantly between lenders; use a whole-of-market broker who can access deals unavailable directly to consumers and often secure better rates through volume discounts. Consider total costs not just the interest rate — a 4.7% rate with £999 arrangement fee might cost more overall than 4.8% with no fee depending on loan size and how long you keep the mortgage. Check allowed overpayment limits if you plan to pay extra — some deals restrict overpayments or charge hefty early repayment charges that negate the interest savings. Factor in all home buying costs: survey fees (£400-1,500), legal fees (£850-1,500), stamp duty (use our calculator), removal costs (£300-1,200), and immediate repairs or furnishings. Most lenders will lend 4.5× your annual salary though some stretch to 5-5.5× for high earners; calculate the maximum you can borrow but consider whether you can comfortably afford the payments long-term, especially if rates rise or income falls. Build in a buffer for interest rate rises when calculating affordability — if your budget is tight at current rates, a 2% rise could make payments unaffordable. First-time buyers should check Help to Buy eligibility and Lifetime ISA bonuses which add 25% government contribution up to £1,000 annually on £4,000 saved. Consider property location carefully as Northern areas often offer much better value than London/Southeast, meaning smaller mortgages and lower monthly payments for equivalent or larger properties. Remember that leasehold properties have ground rent and service charges on top of mortgage payments, significantly affecting affordability. Finally, don't max out your budget — keeping payments to 30% of take-home income provides financial flexibility for life's unexpected costs and opportunities.