Home loan repayments and total interest.
Monthly repayment
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Total interest
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Total repaid
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Your breakdown
Updates live as you type| Item | Amount |
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Worked example
Take a $600,000 home loan at 6.5 percent over a 30 year term, a typical NZ scenario. The annuity formula converts the annual rate into a monthly rate of about 0.5417 percent and spreads the loan across 360 monthly payments. That produces a monthly repayment of $3,792. Over the full 30 years you make 360 of those payments, totalling $1,365,267.
Of that total, $600,000 is the principal you borrowed and the other $765,267 is interest, more than the house itself. This is why even small rate changes matter so much over a 30 year term. Many New Zealanders pay fortnightly instead of monthly. Paying half the monthly amount, about $1,896, every fortnight means 26 half-payments a year, equal to 13 monthly payments rather than 12, and that one extra payment each year quietly shortens the loan and cuts total interest.
| Item | Amount |
|---|---|
| Loan amount | $600,000 |
| Monthly repayment | $3,792 |
| Total interest paid | $765,267 |
| Total repaid over 30 years | $1,365,267 |
How it is calculated
The repayment uses the standard amortising loan formula. The annual interest rate is divided by 12 to get a monthly rate, and the term in years is multiplied by 12 to get the number of payments. The formula then finds the fixed payment that fully clears the loan over that many months, with each payment covering the interest on the remaining balance first and the rest reducing the principal. Early payments are mostly interest, while later payments are mostly principal, which is why making extra repayments early saves the most. Total interest is simply the sum of all repayments minus the original loan amount. This calculator assumes a constant rate, whereas most NZ loans are split across fixed terms that reprice every one to five years.