UK Mortgage Calculator
TL;DR
- Enter purchase price, deposit, interest rate, and term to get your estimated monthly repayment
- This calculator also estimates Stamp Duty Land Tax (SDLT) — something most mortgage tools leave out
- A 0.5% rate difference on a £250,000 loan over 25 years costs roughly £65 more per month
- Scotland uses LBTT and Wales uses LTT — those need separate government calculators for exact SDLT figures
- Everything runs in your browser; no signup, no data sent anywhere
Buying property in the UK means budgeting two numbers: your monthly mortgage repayment and your upfront Stamp Duty liability. Most online tools only show the first. This UK mortgage calculator shows both — enter your purchase price, deposit, rate, and term for a realistic picture before you speak to a lender.
How do I calculate my monthly UK mortgage repayment?
The standard amortization formula:
Monthly payment = P × (r(1+r)ⁿ) / ((1+r)ⁿ − 1)
Where P is the loan amount (purchase price minus deposit), r is the monthly rate (annual rate ÷ 12), and n is total payments (years × 12).
For a £200,000 loan at 5.5% over 25 years: monthly payment ≈ £1,227.
| Loan | Rate | Term | Monthly Payment | Total Interest |
|---|---|---|---|---|
| £200,000 | 5.0% | 25 yrs | £1,169 | £150,700 |
| £200,000 | 5.5% | 25 yrs | £1,227 | £168,100 |
| £200,000 | 6.0% | 25 yrs | £1,289 | £186,700 |
| £250,000 | 5.5% | 25 yrs | £1,534 | £210,200 |
| £250,000 | 5.5% | 30 yrs | £1,419 | £261,000 |
The £115/month difference between a 25-year and 30-year term on £250,000 at 5.5% adds up to over £50,000 in extra interest over the life of the loan.
How is Stamp Duty Land Tax calculated on a UK property purchase?
SDLT is charged in bands — like income tax brackets, not as a flat rate on the total price.
For residential purchases in England and Northern Ireland (2024 rates):
| Purchase Price Band | SDLT Rate |
|---|---|
| Up to £250,000 | 0% |
| £250,001 to £925,000 | 5% |
| £925,001 to £1,500,000 | 10% |
| Over £1,500,000 | 12% |
On a £350,000 purchase: 0% on the first £250,000 + 5% on the remaining £100,000 = £5,000 SDLT.
First-time buyers get a different threshold (0% up to £425,000 as of late 2022 — verify the current rate with HMRC as this changes). Scotland uses LBTT and Wales uses LTT, each with their own bands — for those regions, the monthly repayment math from the UK mortgage calculator is accurate but use official government tools for the tax figure.
What''s the difference between a fixed-rate and tracker mortgage?
Fixed-rate: Your interest rate stays the same for a set period — typically 2, 5, or 10 years — regardless of Bank of England base rate movements. Your monthly payment is predictable. After the fixed period, you move to the lender''s Standard Variable Rate (SVR) unless you remortgage.
Tracker: Your rate moves with the Bank of England base rate plus a set margin (e.g., "base rate + 1%"). When the base rate rises, your payment rises. When it falls, your payment falls.
For a tracker mortgage, plug in today''s rate to see the current payment — but run three scenarios: current rate, +0.5%, and +1%. That stress-test shows whether the mortgage remains affordable if rates move against you.
How much deposit do I need and how does it affect my rate?
The minimum is usually 5% of the purchase price. On a £300,000 property, that''s £15,000. The rate available at 5% deposit is significantly higher than at 25%.
According to UK Finance data (2023), the average first-time buyer deposit was 22% of the purchase price. The interest rate difference between a 5% and 25% deposit can be 1–1.5 percentage points — on a £250,000 mortgage, that''s roughly £150–£200 more per month at the lower deposit.
Most lenders'' best rates are available at 60% or 75% LTV (Loan-to-Value). Your deposit determines your starting LTV; as you pay down the mortgage, your LTV falls and you may qualify for better rates when you remortgage.
For a full payment schedule showing exactly how your balance reduces year by year, the mortgage amortization calculator generates the complete table — useful for planning overpayments or understanding your equity at any point in the term.
Should I compare monthly payment or total interest cost?
Both — they answer different questions.
Monthly payment tells you whether the mortgage fits your budget today. Most UK lenders require your mortgage payment to be no more than 35–45% of monthly net income during affordability checks.
Total interest cost tells you the real price of the loan. A 30-year term on £200,000 at 5.5% costs over £50,000 more in total interest than a 25-year term at the same rate. That''s a significant number hiding inside what looks like a small monthly saving of £115.
The mortgage amortization calculator shows both the month-by-month breakdown and the running total, making it clear exactly when your balance crosses key thresholds.
Frequently Asked Questions
How accurate is a UK mortgage calculator?
Accurate for standard repayment mortgages at a fixed rate. The tool uses the exact amortization formula lenders use. What it doesn''t include: arrangement fees (typically £999–£1,999, which can be added to the loan), insurance, and lender-specific affordability criteria based on income and outgoings. The figure is a reliable starting estimate — not a mortgage offer.
What is a good UK mortgage interest rate right now?
Rates change with the Bank of England base rate and lender competition. As of 2024, 5-year fixed rates were broadly in the 4.5–5.5% range for buyers with a 25%+ deposit. Always compare through a whole-of-market broker — they access rates not available directly. Enter any rate you''ve been quoted into the UK mortgage calculator to see the repayment figure.
What is the average UK mortgage payment?
UK Finance reported the average monthly mortgage payment for first-time buyers at around £1,050–£1,200 in 2023, varying significantly by region. London averages are substantially higher. Your own figure depends on local property prices and the rate you qualify for.
Can I use this calculator for a buy-to-let mortgage?
The repayment math is the same, but buy-to-let mortgages typically require a 25% minimum deposit, and lenders assess affordability against rental income rather than personal income. SDLT also includes a 3% surcharge on additional properties — the SDLT estimate in this calculator won''t include that surcharge, so factor it in separately.
What does LTV mean on a mortgage?
Loan-to-Value is the ratio of your mortgage to the property''s value. A £180,000 mortgage on a £200,000 property is 90% LTV. Lower LTV means lower risk for the lender and better rates for you. As you repay the mortgage, your LTV falls — which is why remortgaging after a few years of payments, or after the property rises in value, often unlocks a better rate.
Is stamp duty included in a mortgage?
Not automatically. SDLT must be paid from your own funds, usually within 14 days of completing. It comes on top of your deposit and legal fees — which is why knowing your SDLT bill before you commit to a purchase is important. The UK mortgage calculator shows the estimate so this cost doesn''t catch you off guard.
How much can I borrow for a UK mortgage?
Most UK lenders offer 4–4.5× your annual income. On a £60,000 salary, that''s typically £240,000–£270,000. Some lenders stretch to 5× or 5.5× for higher earners or certain professions. Lenders also stress-test against rates roughly 3% above your starting rate to confirm affordability if rates rise.
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