Mortgage Overpayment Calculator

Use the free Mortgage Repayment Calculator to test mortgage overpayments, compare interest saved, and download a CSV of the repayment path.

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Estimate how regular mortgage overpayments may change payoff time, total interest, and monthly repayment comparisons.

Compare a standard repayment path with an overpayment scenario.
Estimate monthly repayment, total interest, and payoff timing.
Download results for spreadsheet comparison.

Use the tool

Open the calculator or utility

This page is built around a specific search question. The linked TallyKind tool does the live calculation or analysis with editable inputs and clear outputs.

Open mortgage repayment calculator Mortgage affordability Money tools

Overpayments

What to model before paying extra

Overpayments can reduce interest and shorten the term, especially when made early, but the effect depends on the balance, interest rate, term, and lender rules.

The calculator uses constant-rate repayment maths with optional monthly overpayments so you can compare the broad effect before checking your mortgage account.

Enter balance, deposit or loan amount, rate, term, and monthly overpayment.
Check whether the interest saved outweighs other uses for the money.
Use the CSV download to compare multiple scenarios.

Assumptions

Check lender rules and rate changes

Many mortgages have annual overpayment limits, early repayment charges, fixed-rate periods, or recalculated payment rules that affect the real outcome.

Treat the result as a planning estimate and confirm overpayment rules with the lender before acting.

Check whether overpayments reduce term, payment, or both.
Check early repayment charges and annual overpayment limits.
Retest if the rate, product, or term changes.

FAQs