UK Mortgage Calculator
Work out your monthly mortgage payments, total interest, stamp duty and how much an overpayment could save you — with interactive charts built for UK buyers.
Where your money goes
Share of everything you repay to the lender: borrowed capital vs interest.
Mortgage balance over time
Remaining loan balance at the end of each year.
How a UK mortgage works
A UK mortgage lets you buy a home with a long-term loan, repaid in monthly instalments — typically over 25 years, although 10-to-40-year terms are common. Every payment covers two things: part of the loan itself (the capital) and the lender's charge for borrowing (the interest).
Most UK mortgages are fixed for an initial period — commonly 2 or 5 years — meaning your rate and monthly payment stay the same during that time. As of September 2026, the average two-year fixed rate is around 5.3–5.7% and the average five-year fix around 5.5–5.8%, with the Bank of England base rate held at 3.75%. A single percentage point on the rate can change your monthly payment by hundreds of pounds on a typical loan.
Repayment vs interest-only mortgages
The calculator supports both UK mortgage types:
- Repayment (capital and interest): each payment reduces the loan balance as well as paying interest. By the end of the term you own the home outright. This is what the vast majority of UK buyers choose.
- Interest-only: each payment covers the interest only, so the loan balance never falls. You must have a separate repayment plan — such as savings, investments or a future property sale — to clear the original loan at the end of the term. Lenders set strict criteria for these.
Because an interest-only payment covers interest alone, the monthly figure looks attractively low — but the full loan still has to be repaid at the end, and you pay far more interest over the life of the loan.
The monthly payment formula, explained simply
Behind the monthly payment figure is the standard amortisation formula used by lenders everywhere:
M = P × r(1+r)n ÷ ((1+r)n − 1)
Here P is the loan amount, r is the monthly interest rate (annual rate divided by 12) and n is the total number of monthly payments. It finds the fixed payment that clears the loan exactly, with interest, by the final month.
A simple example: borrow £270,000 at 5% over 25 years (300 payments). The monthly rate is 0.05 ÷ 12 ≈ 0.004167, and the formula gives about £1,578 per month — the figure the calculator shows for those numbers. In the early years most of each payment goes to interest; as the balance falls, more of it pays down the capital.
Stamp duty in 2026 (England & Northern Ireland)
Stamp Duty Land Tax (SDLT) is paid on top of the purchase price and is a major part of your upfront costs. Since 1 April 2025 the temporary higher thresholds have expired, so these are the 2026 bands. Tax is charged only on the slice of the price within each band:
| Portion of property price | Standard rate | First-time buyer rate |
|---|---|---|
| Up to £125,000 | 0% | 0% |
| £125,001 – £250,000 | 2% | 0% (up to £300,000) |
| £250,001 – £500,000 | 5% | 5% on £300,001 – £500,000 |
| £500,001 – £925,000 | 5% | No relief — standard rates |
| £925,001 – £1,500,000 | 10% | No relief — standard rates |
| Above £1,500,000 | 12% | No relief — standard rates |
So a first-time buyer paying £300,000 in 2026 owes £0 in stamp duty, while a mover buying the same home pays £5,000 (2% on £125,001–£250,000 plus 5% on £250,001–£300,000). First-time buyer relief applies only up to £500,000 — above that, standard rates apply in full. The calculator applies these bands automatically; for a full band-by-band breakdown see an independent SDLT calculator for 2026, and this stamp duty tax guide explains the current thresholds in detail.
Worked example: £300,000 home, 10% deposit
The average UK home costs around £298,000 according to Halifax's August 2026 index, so a £300,000 purchase is a realistic national example. Here is what the calculator returns for a typical buyer:
| Figure | Value |
|---|---|
| Property price | £300,000 |
| Deposit (10%) | £30,000 |
| Loan amount | £270,000 |
| Loan-to-value | 90% |
| Term / rate | 25 years at 5% |
| Monthly payment | £1,578.39 |
| Total interest | £203,517.93 |
| Stamp duty (first-time buyer) | £0 |
| Cash needed upfront | £30,000 |
A mover buying the same property would need £35,000 upfront (£30,000 deposit plus £5,000 stamp duty). If the price were the typical first-time-buyer asking price of about £225,000, a 10% deposit gives a £202,500 loan — £1,183.79 a month at 5% over 25 years, with no stamp duty for a first-time buyer.
What overpaying does to your mortgage
Overpaying — putting extra money towards the loan each month — is one of the most powerful levers a borrower has, because the saving compounds: every extra pound reduces the balance, so less interest accrues, so more of the next payment hits the capital. Most UK lenders let you overpay up to 10% of the balance a year without an early repayment charge.
Take the £270,000 loan above at 5% over 25 years. Overpay by £200 a month and the loan clears in about 20 years and 1 month — nearly 5 years early — saving roughly £45,264 in interest. Enter any extra amount in the calculator and the green line on the balance chart shows how much faster the balance falls.
How much can you borrow?
Lenders typically lend around 4 to 4.5 times your annual income, and they stress-test your budget against higher rates. Your deposit also matters: a bigger deposit means a lower loan-to-value ratio, which usually unlocks cheaper rates. Use our UK take-home pay calculator to see your real after-tax income — the number lenders actually look at — and our pay raise calculator to see how a salary increase changes what you can afford. For wider context, see our guide to the average salary in the UK in 2026. And this September 2026 mortgage market update shows how funding costs have been pushing average fixes higher even while base rate sits at 3.75%.
Know your take-home pay first
Lenders judge affordability on after-tax income. Check your UK take-home pay, then come back and test the mortgage it affords.
Open the UK take-home pay calculatorFrequently asked questions
How much mortgage can I afford in the UK?
Most lenders offer around 4 to 4.5 times your gross annual salary, subject to an affordability check. A £40,000 salary typically supports a loan of £160,000–£180,000. Enter your loan size above to see the monthly cost.
What is a good mortgage rate in the UK in 2026?
As of September 2026 the average two-year fixed rate is around 5.3–5.7% and the average five-year fix around 5.5–5.8%. Larger deposits usually get deals below the average.
Do first-time buyers pay stamp duty in 2026?
First-time buyers pay no stamp duty on homes up to £300,000 in England and Northern Ireland, then 5% on the portion from £300,001 to £500,000. Above £500,000 no first-time buyer relief applies and standard rates are charged.
How much deposit do I need for a UK mortgage?
Most lenders accept deposits from 5%, but 10% or more gives access to better rates. On a £300,000 home, 10% is £30,000 — plus stamp duty, fees and moving costs.
Does overpaying my mortgage reduce the term or the monthly payment?
Most UK lenders reduce the remaining term by default, which maximises the interest saved; some let you reduce the monthly payment instead. This calculator assumes term reduction.
Figures are indicative and for planning purposes only — always confirm exact payments with your lender or mortgage adviser. This page is not financial advice.