Free Mortgage Repayment Calculator for New Zealanders
Work out your weekly, fortnightly or monthly repayments on any New Zealand home loan, plus the total interest and the principal-to-interest split.
Your loan
Based on a $650,000 loan at 6.50% over 30 years.
About our Mortgage Repayments Calculator
Three numbers go into our Mortgage Repayments Calculator: the loan amount, the annual interest rate, and the term in yearsLoan termNumber of years the loan must be repaid over (commonly 25-30 for NZ home loans).View in glossary →.
A single repayment comes back out, set to weekly, fortnightlyFortnightlyEvery two weeks; the default repayment frequency for most NZ home loans.View in glossary →, or monthly so it matches how you actually pay your bills.
The maths is the same amortising-loan formulaAmortisationEqual loan payments that gradually shift from mostly interest to mostly principal over the loan term.View in glossary → that ANZ, ASB, BNZ, Westpac, and Kiwibank quietly run on their own websites when they quote you a number. We have made the working transparent and the result instant, so you can scan a hundred different scenarios in the time it takes to fill out a bank enquiry form.
The repayment figure assumes a fixed rate that holds for the full term. That is not how most New Zealand mortgages actually play out.
The Reserve Bank's lending data shows the average new owner-occupier loan refixes every one to three years, and the rate moves with each refix. Treat the result as a planning baseline, not a 30-year forecast.
How to use it
Type your loan amount into the first field, or drag the slider for a quick scan.
Set the interest rate your bank has actually offered, or pick a current 1-year fixed average from interest.co.nz if you are still shopping.
Choose a term in years (the standard NZ first-home loan runs 25 to 30) and pick how often you want to repay.
The repayment, total interest, and the principal-to-interest split update the moment you adjust anything, so two-handed comparisons take seconds.
The Reset button returns the inputs to the $650,000 loan, 6.50% rate, 30-year term, fortnightly schedule defaults that the calculator loads with.
Why use it
A mortgage repayment is the biggest single line in most New Zealand household budgets, and it shifts by hundreds of dollars per fortnight as the rate or term moves.
Knowing the actual figure before you commit puts you in the bank conversation with the same numbers your lender is working from.
The calculator also surfaces something most first-home buyers do not see until it is too late, namely how much of every payment in the first decade goes to interest rather than to actually owning more of the house.
Run the numbers a few different ways before you sign anything.
The maths behind it
M = P × [r(1 + r)n] / [(1 + r)n − 1] Where P is the loan PrincipalPrincipalOriginal amount borrowed on a loan, or the starting capital in an investment.View in glossary →, r is the periodic interest rate (annual rate divided by payments per year), n is the total number of payments (years × payments per year), and M is the per-period repayment. For a $650,000 loan at 6.50% over 30 years paid fortnightly, that gives r of 0.0025 and n of 780, returning a payment of $1,896.
Worked example
Mason and Whitney, three-bedroom first home in Hamilton.
Mason and Whitney have scraped together a 20% deposit on a $720,000 house, leaving $576,000 to borrow.
Their bank, ASB, offers a one-year fixed rate of 5.95%. They choose a 30-year term paid fortnightly so the schedule lines up with payday.
The calculator returns $1,594 per fortnight. Across the full life of the loan, that compounds to roughly $1.24 million in total payments, of which around $670,000 is interest.
When the year is up, Mason and Whitney will refix at whatever rate is on offer, and their fortnightly figure resets accordingly.
Weekly, fortnightly, or monthly
Banks usually let you choose how often you repay, and the choice matters more than people expect.
The two scenarios below use the same $650,000 loan at 6.50% over 30 years. The only thing that changes is how the repayment is split across the year.
Pay monthly
- Per payment
- $4,108
- Annual paid
- $49,296
- Total interest
- $828,880
- Loan ends
- 2055
Pay fortnightly (half-monthly)
- Per payment
- $2,054
- Annual paid
- $53,404
- Total interest
- $689,400
- Loan ends
- 2051
The fortnightly column above sets the payment at half the monthly figure, which is how most NZ banks default the schedule.
Because there are 26 fortnights but only 12 months in a year, you end up squeezing 13 monthly payments worth into a year instead of 12. That single change clears a $650,000 loan four years earlier and shaves around $140,000 off the total interest.
Weekly works on the same logic with 52 payments, but the practical gap between weekly and fortnightly is small. The big jump is from monthly to fortnightly.
Tips and insights
✓ Worth doing
- Pay fortnightly. The half-monthly cadence packs 13 monthly payments into a year without you noticing.
- Round up to the nearest $50 or $100 a fortnight. Most NZ banks let you set a higher repayment than the required minimum.
- Split your loan across two or three fixed terms. A 1-year and 3-year split hedges against the chance that rates move sharply at refix time.
- Check whether your lender offers an offset or revolving-credit facility. BNZ TotalMoney and Kiwibank's revolving credit let idle savings reduce the daily interest charged.
✗ Common pitfalls
- Locking in a 30-year term and never reviewing the schedule after a pay rise or windfall.
- Refixing for 5 years just because the headline rate is slightly cheaper, without weighing the cost of being locked in.
- Assuming the bank's stress-test rate is what you will actually repay. It is a serviceability hurdle, nothing more.
- Choosing weekly over fortnightly hoping for a meaningful saving. The numbers barely move.
Things to keep in mind
- Fixed-rate resets. The calculator holds your rate constant for the full term. Most NZ borrowers refix every one to three years, so the actual repayment moves with each new fixed rate. Re-run the numbers every refix.
- Bank stress tests. Lenders test serviceability at a rate two to three percentage points above the contract rate, partly under RBNZRBNZReserve Bank of New Zealand; sets the OCR, regulates banks, enforces LVR and DTI caps.View in glossary → guidance. The figure here is what you would pay, not what the bank uses to decide whether to lend.
- Other home costs. The repayment shown does not include council rates, home insurance, body-corporate fees on apartments, or optional mortgage repayment insurance. Those land separately on your monthly budget.
- Investment property tax. If the loan is for a rental, IRD's interest-deductibility rules affect your real after-tax cost. From April 2025, interest is again fully deductible against rental income, but the calculator does not model that. Run rental scenarios through the rental cash-flow calculator for a fuller picture.
Common mistakes
Doubling a fortnightly figure to get monthly
Two fortnights at $1,896 add up to $3,792, but the monthly equivalent is $4,108. The fortnightly cadence carries an extra payment per year baked in.
Treating the bank's stress-test rate as the repayment
Banks test your serviceability against a rate roughly two to three percentage points above the contract rate. That is a hurdle, not a payment. The figure on this page is the real one.
Forgetting the rate resets every fixed term
The 30-year amortisation only holds if the rate stays put for 30 years. It will not. Plan for a refix every one to three years and rerun the calculator each time.
NZ-specific notes
Glossary
- Amortising loan
- A loan where each payment includes both interest and principal, so the balance reaches zero on the last day of the term.
- Principal
- The dollar amount you actually borrowed and still owe at any point in the loan.
- Term
- How long the loan runs, in years. Standard NZ owner-occupier mortgages are 25 to 30 years.
- Periodic rate
- The annual interest rate divided by the number of payments per year (52 weekly, 26 fortnightly, 12 monthly).
- LVR
- Loan-to-Value Ratio. The loan amount divided by the property value, written as a percentage.
- Test rate
- The higher rate a bank uses when stress-testing your serviceability, currently around two to three percentage points above the contract rate.
- Break fee
- A charge banks apply when you exit a fixed-rate loan before its term is up. Sized to compensate the bank for lost interest.
- Refix
- The point a fixed-rate term ends and you choose a new fixed rate at the bank's then-current pricing.
Who this calculator is for
Working out what's actually affordable
Run different deposit sizes against the price range you are looking at. Pair with the borrowing capacity calculator for the income side of the same question.
Comparing your current loan to a new offer
Plug your remaining balance against the new bank's offered rate. Run the break-fee calculator alongside it before you decide to switch mid-term.
Sizing the cash flow on a rental purchase
The repayment is one of three big inputs into a rental's cash position. Settle the loan side here, then layer in rent, rates, insurance, and tax in the rental cash-flow calculator.
FAQs
Does the figure include rates, insurance, or body corporate fees?
No. The calculator returns the loan repayment only. Council rates, home insurance, body-corporate fees on apartments, and optional mortgage repayment insurance are separate ongoing costs. Add them on top when you build your monthly budget.
What rate should I use?
Use the rate your bank has actually offered, or a current 1-year or 2-year fixed average from interest.co.nz if you are still shopping. The default of 6.50% is a mid-2026 reference point, not a recommendation. Rates change weekly.
What if I want to make extra repayments?
Most NZ banks let you raise the scheduled repayment, make lump-sum payments, or pay off a fixed-rate loan early (with a possible break feeBreak feeCharge for exiting a fixed-rate mortgage early; depends on rate movement and time remaining.View in glossary →). The lump-sum calculator shows the impact of one-off extra payments, and the break-fee calculator covers mid-term exits.
Why does total interest sometimes exceed the loan amount?
Compounding works against you when you are the borrower. At 6.5% over 30 years, you pay back roughly $2.28 for every $1 borrowed. Shorter terms and lower rates flip the maths the other way. For a typical first-home loan over 30 years, paying more than 100% of the principal in interest is normal.
Does the calculator account for fixed-term resets?
No. It uses one rate for the full term, which gives a clean planning baseline but not a forecast. In real life you will refix every one to three years, and the repayment changes with each new rate. Re-run the numbers every refix.
Will the bank quote me exactly this number?
Within a dollar or two, yes. Banks use the same amortising formula. Tiny rounding differences come from how each lender computes per-period rates and whether they capitalise establishment fees into the principal. The figure here is the underlying maths.
References & sources
- Reserve Bank of New Zealand, "Loan-to-value ratio (LVR) restrictions". rbnz.govt.nz
- Reserve Bank of New Zealand, "Bank lending statistics, monthly release". rbnz.govt.nz
- REINZ, "House Price Index, monthly property report". reinz.co.nz
- Inland Revenue, "Interest deductions on residential investment property". ird.govt.nz
- Stats NZ, "Household income and housing-cost statistics, year ended June 2025". stats.govt.nz