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Mortgage protection calculator

Written and reviewed by Sanjeev Yoganathan · Last reviewed 10 June 2026

Estimate your mortgage protection needs and compare level term (sum assured stays constant) against decreasing term (sum assured reduces roughly in line with a repayment mortgage). Both types have their place depending on your mortgage and broader needs.

Note: We don't store what you type, and we never ask for medical or sensitive personal details.

Used to model the decreasing term schedule.

Assumptions and methodology

Lump sum need = outstanding mortgage + other debts + desired additional support − existing cover − savings. The decreasing term schedule uses standard mortgage amortisation: B(n) = P × [(1+i)^N − (1+i)^n] / [(1+i)^N − 1]. An assumed coverage rate slightly above the mortgage rate is applied to ensure cover stays above the outstanding balance.

Common mistakes to avoid

  • Choosing a joint life policy that only pays once — consider two single-life policies for broader protection.
  • Under-buying the term — check it at least covers the full remaining mortgage term.
  • Not considering interest-only mortgages — the balance does not reduce, so decreasing term may not be appropriate.

Frequently asked questions

Written and reviewed by Sanjeev Yoganathan · Last reviewed 10 June 2026

Disclaimer

This is a simplified estimate based on the assumptions shown above. It isn't a quote, and a real insurer may arrive at a different figure. Use it as a starting point, then check the details with your insurer or adviser.