Extra Mortgage Repayment Calculator

How Extra Mortgage Repayments Cut Your Interest

Enter your loan amount, interest rate, term and repayment frequency, then add a regular extra repayment, a one-off lump sum, or both. The calculator shows your new payoff time, total interest saved, and a year-by-year comparison against your standard repayment schedule.

Why Extra Repayments Work

Worked Example

A $500,000 loan at 6% p.a. over 30 years, paid monthly, has a standard repayment of $2,997.75 and racks up $579,190.95 in total interest. Add an extra $200 a month (a new total repayment of $3,197.75) and the loan is paid off in 25.5 years instead of 30 — saving $103,144.89 in interest and 4.5 years off the loan term.

Frequently Asked Questions

How does an extra mortgage repayment calculator work?

Enter your loan amount, interest rate, term and repayment frequency, then add how much extra you plan to pay each period (and/or a one-off lump sum). The calculator compares your standard repayment schedule against one with the extra amount included, showing how much interest you'd save and how many years sooner the loan would be paid off.

How much can extra home loan repayments actually save me?

It depends on your loan size, rate, remaining term and how much extra you pay — but even modest amounts add up because extra repayments go straight to principal, which reduces the interest charged on every future repayment. For example, an extra $200 a month on a $500,000 loan at 6% over 30 years saves about $103,000 in interest and pays the loan off 4.5 years sooner.

Does it matter if I pay extra weekly, fortnightly or monthly?

Paying more frequently (weekly or fortnightly instead of monthly) shaves a small amount off your interest bill on its own, because interest has less time to accrue between payments. But the bigger lever by far is the total extra dollar amount paid per year — select whichever frequency matches your actual pay cycle and enter the extra amount for that period.

What's the difference between a regular extra repayment and a lump sum?

A regular extra repayment is an ongoing top-up added to every scheduled repayment (e.g. an extra $100 every month, for the life of the loan). A one-off lump sum — a bonus, inheritance or tax refund, for example — is applied once, straight off the balance, at the start. You can enter either, or both, and the calculator will combine their effect.

Why is my "new repayment" higher than my standard repayment?

The "new repayment" shown is your standard repayment plus the extra amount you entered — it's the total you'd actually pay each period, not a separate number. If you want to see the impact of extra repayments without increasing your committed outgoings, check whether your loan has a redraw facility or offset account, which can achieve a similar effect more flexibly.

What if my extra repayment doesn't cover much interest?

If an extra repayment is very small relative to the interest accruing, it will still help, just by a smaller amount — the calculator always compares like-for-like, so you'll see the real (even if modest) time and interest saved for whatever amount you enter.

Are there limits on how much extra I can repay on my mortgage?

Many Australian lenders cap extra repayments on fixed-rate loans (often a set dollar amount per year before break costs or fees apply), while variable-rate loans are usually unlimited. This calculator assumes no such cap — check your loan contract or ask your lender before committing to a large or ongoing extra repayment amount.