Mortgage Calculator UK
This UK mortgage calculator estimates the monthly repayment on a British home loan and adds the Stamp Duty Land Tax you would owe on the purchase, giving a fuller picture of the true cost of buying. You enter the property price in pounds and your deposit; the difference is the amount borrowed, which is repaid with a fixed monthly figure over your chosen term. On top of that, it applies England and Northern Ireland's tiered stamp duty bands so you can see the upfront tax alongside the lifetime interest and total cost.
Formula
Loan = Price − Deposit; M = Loan · r(1+r)ⁿ / ((1+r)ⁿ − 1); Stamp duty = tiered bands on Price
- Price
- Property purchase price in pounds (£)
- Deposit
- Cash deposit paid upfront in pounds
- M
- Monthly repayment on the loan amount
- r
- Monthly interest rate = annual rate ÷ 12 ÷ 100
- n
- Number of monthly payments = term in years × 12
How it works
- Enter the property price in £ and your deposit. The deposit is subtracted from the price to give the loan amount, and the monthly repayment is calculated with the standard repayment-mortgage annuity formula at your chosen interest rate and term.
- Stamp Duty Land Tax is computed on the full property price using tiered bands: nothing up to £250,000, 5% on the slice from £250,000 to £925,000, 10% from £925,000 to £1.5M, and 12% above £1.5M.
- The results show the monthly payment, the stamp duty due, the total interest over the term, and a total cost that combines all repayments with the deposit and stamp duty.
Worked example
A £400,000 property with a £40,000 deposit, a 5% annual rate, and a 25-year mortgage term.
- Loan amount: 400,000 − 40,000 = £360,000.
- Monthly repayment: 360,000 × 0.0041667 × 1.0041667³⁰⁰ ÷ (1.0041667³⁰⁰ − 1) = £2,104.52.
- Stamp duty: 0% to £250,000 = £0, plus 5% on (400,000 − 250,000) = 5% × 150,000 = £7,500.
Monthly repayment is £2,104.52, stamp duty is £7,500, total interest is about £271,357, and the total cost including deposit and stamp duty is roughly £678,857.
Frequently asked questions
- How is UK Stamp Duty Land Tax calculated here?
- It uses tiered bands on the purchase price: 0% up to £250,000, 5% on the portion from £250,000 to £925,000, 10% from £925,000 to £1.5M, and 12% above that. Only the slice of price within each band is charged at that band's rate.
- Does this reflect first-time buyer relief or additional-property surcharges?
- No. It applies the standard residential bands only. First-time buyer relief, the additional 3% surcharge on second homes and buy-to-let, and the different rules in Scotland (LBTT) and Wales (LTT) are not modeled.
- Is this a repayment or interest-only mortgage?
- It models a capital-and-interest repayment mortgage, where each monthly payment clears both interest and a slice of the loan so the balance reaches zero by the end of the term. Interest-only mortgages, where the balance stays fixed, are not covered.
- Does the total cost include fees and insurance?
- The total cost combines all monthly repayments with your deposit and the stamp duty. It does not include arrangement or valuation fees, buildings insurance, or ground rent, so budget for those separately.