About Mortgage Overpay

Mortgage Overpay is designed to give UK homeowners a faster, clearer view of how mortgage overpayments could change payoff date, interest paid, and total term.

What the site is for

Simple scope is part of the value.

The site focuses on quick decision support rather than account setup, dashboards, or linked data. Version 1 is deliberately web-first, fast, and low friction.

The calculator uses a repayment mortgage model with monthly compounding and reducing balance assumptions to estimate time saved and interest saved from overpayments.

Assumptions and limitations

Clear limitations build trust.

The tool gives illustrative results, not regulated advice. It does not know your exact mortgage contract, charges, or lender treatment of overpayments, so you should always check your own terms before acting.

Use the calculator with your own figures

If you want to see how the model behaves in practice, the calculator is the fastest place to start.

Try the calculator