Mortgage Overpayment Calculator — Overpay vs Invest
Should you overpay your mortgage or invest the difference? This calculator models your real UK mortgage — repayment or interest-only, with a fixed rate that reverts to the SVR — and shows which use of your spare cash builds the most wealth by the end of the term.
- Compare standard payments, monthly overpayments, a lump sum, and investing instead
- Repayment and interest-only mortgages, with fixed-then-revert (SVR) rates
- Warns when overpayments exceed the typical 10%-a-year penalty-free allowance (ERC)
- Includes stamp duty (with first-time-buyer relief) and an affordability check
This interactive calculator requires JavaScript. Please enable it to run your figures. Estimates only — not financial advice. Actual Maths, a product of Asantagram Ltd.