Mortgage Broker NZ

Mortgage Repayment Calculator NZ

Calculate your weekly, fortnightly, and monthly repayments for any loan amount, interest rate, and term. Includes a rate comparison table so you can see how your repayments change if rates move.

Calculate your repayments

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Current 1-year fixed rates are typically 5–7%. Check the mortgage rates page for current market rates.

How are mortgage repayments calculated?

This calculator uses the standard principal and interest amortisation formula used by New Zealand banks:

Repayment = P × r(1+r)ⁿ ÷ ((1+r)ⁿ − 1)

P = loan principal  |  r = monthly interest rate (annual rate ÷ 12)  |  n = total months (years × 12)
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Monthly vs fortnightly

Paying fortnightly rather than monthly means you make the equivalent of 13 monthly payments per year instead of 12, reducing your loan faster and cutting total interest paid.

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Lower rates = lower repayments

A 1% reduction in your interest rate can reduce monthly repayments on a $500k loan by around $300–$350. The rate comparison table shows exactly how much your repayments change.

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Shorter term = less interest

Choosing a 20-year term over 30 years dramatically reduces total interest paid, though your regular repayments will be higher. Try adjusting the term to compare.

Fixed vs floating rates in NZ

Most New Zealand borrowers fix part or all of their mortgage for a term of 6 months to 5 years. The rest may be on a floating (variable) rate. Each fixed term rolls over at whatever the current market rate is at that time, which means your repayments can change significantly when you refix.

This calculator shows repayments at a fixed rate. In practice, your average rate over the life of the loan will depend on how rates move. A mortgage adviser can help you think through fixing strategy based on the current rate environment.

Frequently asked questions

How are mortgage repayments calculated?
Mortgage repayments use a standard amortisation formula: the repayment is calculated so that equal payments over the loan term pay off both principal and interest in full. The formula is P × r(1+r)ⁿ ÷ ((1+r)ⁿ − 1), where P is the loan principal, r is the monthly interest rate, and n is the total number of months. The calculator applies this formula to show monthly, fortnightly, and weekly equivalents.
Is it better to pay fortnightly or monthly?
It depends on the payment structure. This calculator shows 'accelerated fortnightly' repayments — an amount equal to half the monthly payment. Paid 26 times per year, that totals the equivalent of 13 monthly payments annually rather than 12. Over a 30-year loan this can meaningfully reduce total interest paid and shorten the loan term, typically by two to three years depending on the rate. Many NZ banks offer this structure. Standard (non-accelerated) fortnightly payments — where the annual total equals exactly 12 monthly payments — do not provide the same benefit.
What interest rate should I use in the calculator?
Use the rate on your current or expected loan. For a new purchase, check the mortgage rates page for current market rates, or ask your mortgage adviser what rate you're likely to qualify for. If you're comparing scenarios, try the rate comparison table — it shows how your repayments change at rates 0.5% and 1% above and below your chosen rate.
Does the calculator include fees or other charges?
No — the calculator shows principal and interest repayments only. Your actual mortgage will also involve establishment fees, potentially ongoing fees, and possibly break costs if you fix and then repay early. Ask your mortgage adviser for a full cost comparison before choosing a loan.
What is the difference between interest-only and principal & interest repayments?
With a principal and interest loan, each repayment reduces the loan balance (principal) as well as covering interest. With an interest-only loan, you only pay the interest — the balance stays the same until the interest-only period ends. This repayment calculator shows principal and interest repayments. Interest-only repayments will be lower, but you won't reduce your loan balance during that period.
How does a shorter loan term affect repayments and interest?
A shorter loan term increases your regular repayments but significantly reduces the total interest you pay. For example, a $500,000 loan at 6.5% has monthly repayments of around $3,160 over 30 years, but about $4,200 over 20 years. However, the 20-year option saves over $250,000 in interest. The rate comparison table in this calculator shows interest totals at different rates — try reducing the term and recalculating to see the impact.

Also try the borrowing power calculator

Not sure how much you can borrow? The borrowing power calculator estimates your lending capacity based on your income, deposit, and existing financial commitments.

Borrowing power calculator →All calculators →