Calculate your exact mortgage repayments for any loan size, interest rate, and loan term. Switch between weekly, fortnightly, and monthly to see exactly what you’ll pay — and how much interest you’ll pay over the full term.
On a $600,000 NZ mortgage at 5.79% over 30 years: monthly repayments are approximately $3,529, fortnightly $1,765, and weekly $882. Total interest paid over 30 years would be approximately $670,000. Paying fortnightly rather than monthly is equivalent to making one extra payment per year, reducing the loan term by approximately 3–4 years.
Mortgage Repayment Calculator
Quick Reference — Repayments by Loan Size
Monthly repayments at 5.79% over 30 years:
| Loan amount | Monthly | Fortnightly | Weekly |
|---|---|---|---|
| $400,000 | $2,353 | $1,176 | $588 |
| $500,000 | $2,941 | $1,471 | $735 |
| $600,000 | $3,529 | $1,765 | $882 |
| $700,000 | $4,117 | $2,059 | $1,029 |
| $800,000 | $4,706 | $2,353 | $1,177 |
| $900,000 | $5,294 | $2,647 | $1,324 |
| $1,000,000 | $5,882 | $2,941 | $1,471 |
For in-depth breakdowns by specific loan amount, see:
- Repayments on a $300,000 mortgage
- Repayments on a $500,000 mortgage
- Repayments on a $700,000 mortgage
- Repayments on a $1,000,000 mortgage
How Mortgage Repayments Are Calculated
Mortgage repayments are calculated using the standard amortisation formula:
$$M = P \cdot \frac{r(1+r)^n}{(1+r)^n - 1}$$
Where:
- $M$ = monthly repayment
- $P$ = principal (loan amount)
- $r$ = monthly interest rate (annual rate ÷ 12)
- $n$ = total number of payments (years × 12)
In NZ, interest is typically calculated daily on the outstanding balance — meaning the amortisation formula gives you the baseline, but your actual interest cost depends on when payments are credited and how the bank calculates daily interest accrual.
Weekly vs Fortnightly vs Monthly — Does It Matter?
Paying weekly or fortnightly rather than monthly can meaningfully reduce your total interest cost. Here’s why:
Monthly payments: 12 payments per year Fortnightly payments: 26 payments per year (equivalent to 13 monthly payments) Weekly payments: 52 payments per year (equivalent to 13 monthly payments)
By making 26 fortnightly payments — rather than 12 monthly — you effectively make one extra monthly payment per year. On a $600,000 mortgage at 5.79% over 30 years, this reduces the loan term by approximately 3–4 years and saves approximately $60,000–$80,000 in total interest.
This only applies if the fortnightly/weekly amount is set as half/quarter of the monthly payment (which is how banks typically set it). Simply paying your full monthly repayment in two halves within the same month achieves less.
What Affects Your Actual Rate?
The interest rate in this calculator is the rate your bank applies. Your rate depends on:
- Loan type: Fixed (1–5 years) or floating
- LVR: Higher LVR loans may carry a rate premium
- Lender: Rates vary between banks by up to 0.5%–1.0%
- Negotiation: Banks often discount from advertised rates for strong applications
See Current NZ Mortgage Rates for today’s rates from major banks.
Related Calculators and Guides
- Borrowing Calculator NZ
- Extra Repayments Calculator NZ
- Refinancing Calculator NZ
- How Much Can I Borrow?
- NZ Mortgage Rates and Loan Types
Frequently Asked Questions
What is the repayment on a $600,000 mortgage in NZ?
At 5.79% over 30 years, monthly repayments on a $600,000 NZ mortgage are approximately $3,529, fortnightly $1,765, and weekly $882. Total interest paid over the full 30-year term would be approximately $670,000.
Is it better to pay your NZ mortgage weekly or monthly?
Fortnightly or weekly payments reduce total interest compared to monthly. By making 26 fortnightly payments per year (equivalent to 13 monthly payments), you pay down principal faster and can reduce a 30-year loan term by approximately 3–4 years, saving tens of thousands in interest.
How is a NZ mortgage repayment calculated?
Using the standard amortisation formula: M = P × [r(1+r)ⁿ] / [(1+r)ⁿ − 1], where P is the loan amount, r is the monthly interest rate (annual rate ÷ 12), and n is the number of monthly payments (years × 12). NZ banks typically calculate interest daily on the outstanding balance.
What NZ mortgage rate should I use in a repayment calculator?
Use the rate you’re currently on or the rate you’re considering fixing at. As of April 2026, 1–2 year fixed rates from major NZ banks are approximately 5.2%–5.6%. Check the current NZ mortgage rates page for up-to-date figures from individual banks.
Can I make extra repayments on a fixed-rate NZ mortgage?
Usually yes, but within limits. Most NZ banks allow extra repayments of up to $500–$1,000/week on fixed-rate loans without triggering a break fee. Exceeding the allowed amount may incur a break cost on the fixed-rate portion. Check your specific loan terms.