Principal Payback Milestone Calculator NZ 2026
This calculator shows you exactly when your mortgage crosses each principal payback milestone, from 10% through to 100% repaid, so you can see how your equity in the property builds over time. It matters most around the 20% milestone, because many banks require a loan guarantor or charge low equity fees until that share of the loan is paid back, and passing 50% is a common marker of real progress towards being mortgage-free. You enter your property price, your deposit as either a percentage or a dollar amount, your loan interest rate, your loan term in years, and an optional extra payment with its frequency (weekly, fortnightly or monthly). The calculator works out your loan principal and standard repayment, then builds a month-by-month amortisation schedule to find how long it takes to reach each 10% milestone. Results appear in a table showing the months and years needed under your standard payment and, side by side, under the additional payment, plus a line chart plotting both equity paths over the life of the loan. Use it to see how much time and interest an extra payment could save, or to check when a guarantor could be released. Figures are indicative estimates based on a standard table mortgage and the rates you enter, and are not a substitute for advice from your lender or a licensed financial adviser.
Enter your information into the calculator below, and push Calculate.
| Principal Payback Milestone | Standard Payment Periods (Months) | Standard Payment Periods (Years) | Additional Payment Periods (Months) | Additional Payment Periods (Years) |
|---|---|---|---|---|
| 10% | ||||
| 20% | ||||
| 30% | ||||
| 40% | ||||
| 50% | ||||
| 60% | ||||
| 70% | ||||
| 80% | ||||
| 90% | ||||
| 100% |