UK Mortgage Calculator with Overpayments

How the mortgage calculator works

This UK mortgage calculator estimates your monthly repayment using the standard repayment (capital and interest) formula. Enter the property price and deposit — or switch on 'I know my mortgage amount' to type the loan directly — then set your interest rate and term. The calculator divides the annual rate into monthly periods and amortises the loan across the full term, so every payment covers both interest and a slice of the capital.

Adjust the sliders or type values directly to compare scenarios instantly. A larger deposit lowers both the loan and the loan-to-value; a longer term reduces the monthly payment but increases the total interest you pay over the life of the mortgage.

Understanding loan-to-value (LTV)

Loan-to-value is the size of your mortgage expressed as a percentage of the property price. A £270,000 mortgage on a £300,000 home is 90% LTV. UK lenders usually price products in bands — commonly 60%, 75%, 85%, 90% and 95% — and the lower your LTV, the more competitive the rates you can typically access.

• 5% deposit (95% LTV) is often the entry point for first-time buyers.
• 10–15% deposit (85–90% LTV) generally opens a wider, cheaper range of products.
• 25% or more deposit (75% LTV or lower) tends to reach the most competitive pricing.

How overpayments reduce interest and term

A regular monthly overpayment is applied directly to your outstanding balance, so you pay interest on a smaller amount each month. Even modest overpayments can shorten the term by years and save thousands in interest. Use the overpayment field to see the estimated months saved and interest saved.

Most UK lenders allow penalty-free overpayments of up to 10% of the balance each year, but always check your specific product's terms — overpaying beyond the allowance during a fixed deal can trigger an early repayment charge.

What this calculator can and cannot tell you

The figures shown are educational estimates to help you understand how the numbers fit together. They are not a mortgage offer, a quote, or regulated advice, and they do not account for product fees, insurance, stress-tested affordability rules, or a lender's individual criteria. For figures tailored to your circumstances, speak to a qualified mortgage adviser.