UK Mortgage Calculator with Stamp Duty (2026)

How to Use This UK Mortgage Calculator (2026)

Our free UK mortgage calculator works out your monthly repayment, total interest cost and stamp duty in seconds — using the 2025/26 rates set by HMRC, Revenue Scotland and the Welsh Revenue Authority. Enter your property price, deposit, interest rate and mortgage term, and the calculator does the rest.

What the calculator works out

• Monthly mortgage payment — calculated using the standard UK repayment mortgage formula. The figure assumes a fixed interest rate over the whole term, which is what most lenders quote.
• Stamp duty (SDLT, LBTT or LTT) — applied automatically based on the region you select. First-time buyer relief is built in for England, Northern Ireland and Scotland.
• Loan-to-value (LTV) — the percentage of the property price you are borrowing. Most UK lenders offer their best rates at 60% LTV or lower, with rates increasing as you approach 95%.
• Total cost over the term — your full repayment over the life of the loan, including interest. On a £270,000 mortgage at 4.5% over 25 years, you would repay roughly £450,000 in total.

Why your deposit makes such a big difference

Increasing your deposit from 5% to 10% can save you tens of thousands of pounds in interest because it pushes you into a better LTV band. A bigger deposit usually means a lower interest rate, a lower monthly payment, and lower total interest paid. The calculator’s slider lets you experiment with deposit sizes — and the email-gated PDF report shows the year-by-year amortisation so you can see exactly when the interest portion of your payment falls below the capital portion.

UK stamp duty rates used (April 2025 onwards)

• England & Northern Ireland (SDLT): 0% up to £125,000, 2% £125,001–£250,000, 5% £250,001–£925,000, 10% £925,001–£1.5m, 12% over £1.5m. First-time buyer relief: 0% up to £425,000.
• Scotland (LBTT): 0% up to £145,000 (£175,000 for first-time buyers), 2% £145,001–£250,000, 5% £250,001–£325,000, 10% £325,001–£750,000, 12% over £750,000.
• Wales (LTT): 0% up to £225,000, 6% £225,001–£400,000, 7.5% £400,001–£750,000, 10% £750,001–£1.5m, 12% over £1.5m.

If you are approaching the end of a fixed-rate deal, our remortgaging guide for 2026 walks through your options. And once you have worked out how much house you can afford, it is worth checking your income protection insurance — your mortgage is usually the biggest monthly cost a household has, so protecting that income matters.

Frequently Asked Questions

Is this UK mortgage calculator accurate for 2026?

Yes — it uses the post-April 2025 stamp duty rates and the standard UK repayment mortgage formula. Lenders may add product fees, valuation costs or higher rates at completion, so always confirm your exact monthly payment in your mortgage offer.

Does the calculator include first-time buyer stamp duty relief?

Yes. Tick “I’m a first-time buyer” and the calculator applies the relevant relief for England & NI (0% SDLT up to £425,000) or Scotland (LBTT first-time buyer band up to £175,000). Wales does not currently offer a first-time buyer LTT discount.

Can I see year-by-year repayments and an overpayment scenario?

Yes — the free PDF report includes a year-by-year amortisation table and shows how much interest you could save by paying an extra £100 per month. Enter your name and email to unlock it.

What if I want an interest-only mortgage calculation?

Switch the “Mortgage type” toggle to “Interest-only” and the calculator will show interest-only monthly payments. Remember you will still owe the original capital at the end of the term.

How much deposit do I need for a UK mortgage in 2026?

Most UK lenders accept a minimum 5% deposit, but the best interest rates are reserved for borrowers with 25% or more (75% LTV). Use the deposit slider above to see how each 5% step changes your monthly payment and total cost.