Mortgage Rate Calculator

Our mortgage rate calculator shows how changing interest rates affect your monthly repayment and total cost. Use it to stress-test affordability or see savings when remortgaging.

Enter your mortgage balance, current interest rate, and term. The calculator shows your current monthly payment and the impact of rate changes — either upward movements for stress-testing affordability or downward movements for planning overpayment. The payment change per 0.25% rate movement illustrates the interest rate sensitivity of your specific mortgage. Larger balances and longer terms are more sensitive to rate changes. This is particularly useful during periods of rate uncertainty: knowing that a 0.5% increase adds £X per month to your payment helps you assess whether your budget has sufficient headroom. Compare the results at your current fixed rate versus the estimated SVR you would revert to at the end of your deal.