NZ mortgage calculator · 2026/27
Estimates from a standard repayment formula and rates you can edit.
Built for New Zealand.
Rates current as at 24 July 2026.
Loan of $640,000 · 80.0% LVR
An indicative fixed rate, not a lender quote. Change it to your own.
Extra payments, lump sum, offset, interest-only and stress rate.
On top of the contractual repayment.
Interest is charged on your loan minus this balance.
A buffer banks test you against. Not a forecast.
Repayment per fortnight
$1,676.35
on $640,000 at 5.50% · 30 years
Where $1,307,554 goes over the loan
Increasing your deposit by $20,000 could save $20,861 in interest.
Repayment at nearby terms
Same loan and rate, no extras — a shorter term raises the repayment and usually cuts lifetime interest.
Journey to mortgage-free
Remaining balance at each stop on your current schedule.
This calculator turns a loan amount, interest rate and term into the repayment you would make each week, fortnight or month, and the total interest over the life of the loan. Enter a purchase price and deposit, or the loan directly, and it works out the rest.
It uses a standard repayment formula — the same one lenders use — that spreads the loan and interest evenly across every repayment. Early on, most of each repayment is interest; later, more of it pays down the loan. The interest rate is an editable indicative default of 5.50% that you can change to a rate you have been quoted. It is a starting point, not a lender offer.
Your deposit sets your loan-to-value ratio (LVR). A deposit under 20% means lending above 80% LVR, which the Reserve Bank lets banks ration and which often carries a higher rate or a low-equity fee. The stress-test rate — an editable default of 7.00% — is the higher rate lenders check your repayments against, to see you could still afford them if rates rose.
How the loan is structured changes the total sharply. Because interest is charged on the balance that remains, the first years of a long loan are mostly interest, and small extra payments early save far more than the same amount later. A shorter term raises each repayment but cuts total interest; a longer term lowers the repayment but adds interest. An offset account, or a lump sum, lowers the balance interest is charged on without locking the money away. Fixing your rate holds the repayment steady for a set period, while a floating rate moves with the market and usually allows extra repayments without a break cost. This calculator uses one rate for the whole term, so it shows the shape of a loan rather than the effect of refixing at different rates over time. Even a small difference in the interest rate, held across 30 years, changes the total interest by tens of thousands of dollars, which is why the rate you are quoted matters as much as the amount you borrow.
The result is an estimate, not a loan offer. It does not include establishment or legal fees, insurance, rates, body corporate levies, low-equity premiums, or the break costs a fixed loan may charge for extra repayments. Your actual repayment depends on the rate a lender offers and how often interest compounds.
Worked examples
Both are an $800,000 home at 5.50% over 30 years, fortnightly — the deposit is the only change.
20% deposit
$1,676.35
repayment a fortnight · 80% LVR
A 20% deposit keeps the loan at 80% LVR — standard lending, not high-LVR.
10% deposit
$1,885.89
repayment a fortnight · 90% LVR
A 10% deposit is high-LVR — the bigger loan adds $83,444 of interest over the term.
Short answers on repayments, offset, stress tests and LVR — the rules behind the estimate.
Want the full detail?
Figures depend on the rate and terms you enter. Lenders set their own offers and conditions — the guides walk through how each lever changes the result.