How to use the UK mortgage calculator
- Enter the property price in pounds.
- Enter your deposit. Most lenders want at least 5% to 10%, and the best rates usually start at 25% to 40%.
- Enter the interest rate and the mortgage term in years. Terms of 25 to 35 years are common.
- Choose repayment (capital and interest) or interest-only.
- Choose your Stamp Duty situation: moving home, first-time buyer, buying an additional property, or leave it out.
- Read the monthly payment, total interest, LTV and Stamp Duty, then the breakdown tables.
How the payment is calculated
On a repayment mortgage each payment covers that month's interest and pays off some of the capital, so the debt is cleared by the end of the term. On an interest-only mortgage you only pay the interest, so the payment is lower but you still owe the full amount at the end and need a plan to repay it, such as savings, investments or selling the property. Lenders set the rate in LTV bands, often 60%, 75%, 85%, 90% and 95%, so a slightly bigger deposit can move you into a cheaper band.
Stamp Duty Land Tax rates
Stamp Duty is charged in slices, like income tax: each rate applies only to the part of the price in that band.
| Portion of the price | Standard rate | First-time buyer (price up to £500,000) |
|---|---|---|
| Up to £125,000 | 0% | 0% |
| £125,001 to £250,000 | 2% | 0% |
| £250,001 to £300,000 | 5% | 0% |
| £300,001 to £500,000 | 5% | 5% |
| £500,001 to £925,000 | 5% | relief not available |
| £925,001 to £1.5 million | 10% | relief not available |
| Above £1.5 million | 12% | relief not available |
These are the residential rates from GOV.UK for purchases completing on or after 1 April 2025, and they still apply in 2026. First-time buyer relief applies only if every buyer is a first-time buyer and the price is £500,000 or less; above that, the standard rates apply to the whole price. Buying an additional residential property usually adds 5% to every band, and buyers who aren't UK resident usually pay a further 2%. Scotland (Land and Buildings Transaction Tax) and Wales (Land Transaction Tax) have their own rates, which this calculator doesn't cover.
Worked example
The defaults are a £300,000 property with a £30,000 deposit, a 4.5% repayment mortgage over 25 years, bought by someone moving home:
- Loan: 300,000 − 30,000 = £270,000, an LTV of 90%
- Monthly rate: 0.045 ÷ 12 = 0.00375, and n = 300 months
- Monthly repayment: 270,000 × 0.00375 ÷ (1 − 1.00375^−300) = £1,500.75
- Total repaid: £450,224.31, of which £180,224.31 is interest
- Stamp Duty: 0% of £125,000 + 2% of £125,000 + 5% of £50,000 = £0 + £2,500 + £2,500 = £5,000
- Cash needed up front: £30,000 deposit + £5,000 Stamp Duty = £35,000, before legal and survey fees
As interest-only, the payment would be 270,000 × 0.00375 = £1,012.50, but the £270,000 would still be owed after 25 years. A first-time buyer would pay no Stamp Duty on this property; buying it as an additional property would cost £20,000.
Fixed rates and remortgaging
Most UK mortgages are fixed for 2, 3 or 5 years and then move to the lender's standard variable rate, which is usually much higher. Many borrowers remortgage onto a new deal when the fix ends. This calculator assumes one rate for the whole term, so rerun it at a higher rate to see what the payment could be when your deal ends; at 5.5% the payment on the example loan rises to £1,658.04 a month. Ask about early repayment charges too, since paying off or switching during a fixed period often costs 1% to 5% of the balance.
Frequently asked questions
How much deposit do I need for a mortgage in the UK?
Usually at least 5% of the price, though a 10% deposit opens up more lenders and better rates. Every step down in LTV, to 85%, 75% or 60%, tends to lower the rate on offer.
How much Stamp Duty will I pay as a first-time buyer?
Nothing on the first £300,000, then 5% on the part from £300,001 to £500,000, as long as the price is £500,000 or less. A £450,000 home costs a first-time buyer £7,500, against £12,500 at the standard rates.
Is an interest-only mortgage cheaper?
The monthly payment is lower, but the total cost is higher because the debt never falls. On the example loan you'd pay £303,750 of interest over 25 years and still owe £270,000. Lenders only offer interest-only with a credible repayment plan and often want a large deposit.
Does the calculator work for Scotland and Wales?
The mortgage payment does, since the calculation is the same everywhere. Stamp Duty Land Tax only applies in England and Northern Ireland, so set the Stamp Duty option to leave it out and check Revenue Scotland or the Welsh Revenue Authority for your tax.
Related calculators
- Mortgage Calculator — Your full monthly housing cost, including property tax, insurance, PMI and HOA fees.
- Canadian Mortgage Calculator — Canadian mortgage payments with semi-annual compounding, CMHC insurance and monthly, bi-weekly or weekly payments.
- Mortgage Payoff Calculator — See how extra payments, a lump sum or biweekly payments cut years and interest off your mortgage.
- Mortgage Amortization Calculator — A month-by-month mortgage schedule with dates, PMI until 78% LTV, taxes and insurance, extra payments and a yearly summary.
Results are estimates for educational purposes and are not financial, tax or legal advice. See our disclaimer.