Financial Calculators
Mortgage Overpayment Calculator
Estimate how recurring extra principal payments could shorten your mortgage and reduce interest.
Estimate the effect of an extra mortgage payment before you commit.
Enter your remaining mortgage balance, annual rate, remaining term, and planned recurring extra principal payment. This private browser calculation estimates a fixed-rate monthly schedule and is not financial advice. Check your lender’s prepayment rules, fees, payment allocation, and loan terms before making an overpayment.
Frequently Asked Questions
Everything you need to know about this tool, how it works, and privacy.
How does the mortgage overpayment calculator estimate the result?
It estimates a fixed-rate monthly mortgage schedule from your remaining balance, annual rate, and remaining term, then compares that schedule with the same monthly payment plus your recurring extra principal. It assumes the rate and scheduled payment do not change.
How do recurring extra principal payments affect a mortgage?
Extra principal reduces the outstanding balance sooner, so less interest accrues in later months. The calculator estimates the resulting shorter payoff term and potential interest savings; actual results can differ if your rate, payment, or lender allocation changes.
Do my mortgage details stay private, and should I check with my lender?
Yes. The estimate runs locally in your browser and CodeASystem does not upload or store what you enter. It is not financial advice: confirm your lender’s prepayment rules, fees, payment allocation, and loan terms before making an overpayment.