How to use this UK mortgage calculator
Enter your property price, deposit, mortgage term, and interest rate to instantly see your monthly repayment, total interest paid, and stamp duty (SDLT). Use the overpayment simulator to discover how paying extra each month shortens your term and cuts thousands off your total interest bill.
Repayment vs Interest-Only
A repayment mortgage reduces your loan balance every month, so you own the property outright at the end of the term. An interest-only mortgage keeps the balance unchanged — you only pay the interest each month and need a separate repayment plan (such as an ISA or investment) to clear the capital at the end.
Loan to Value (LTV)
LTV is your mortgage as a percentage of the property's value. A larger deposit means lower LTV and access to better rates. Most lenders reserve their sharpest rates for borrowers at 60% LTV or below. At 90% LTV (10% deposit), you'll typically pay a higher rate but can still get on the ladder sooner.
Stamp Duty Land Tax (SDLT)
SDLT is the tax paid on property purchases in England and Northern Ireland. First-time buyers pay no stamp duty on the first £425,000 of a property priced up to £625,000. Buy-to-let investors and those buying additional homes pay a 3% surcharge on top of standard rates at every band.
Mortgage Overpayments
Regular overpayments reduce your outstanding balance faster, shortening your term and dramatically lowering total interest. Even an extra £100 per month on a £250,000 mortgage can save over £20,000 in interest. Most lenders allow overpayments of up to 10% of the balance per year without an early repayment charge.