Free New Zealand calculator

Mortgage Affordability Calculator NZ: Compare Repayment Scenarios

Enter your home price, deposit and household take-home budget to compare estimated repayments and cash-flow sensitivity at different interest rates.

Calculation sources checked 11 October 2026 · NZD · Estimates only

How does it work?

A mortgage repayment estimate uses the loan principal, nominal annual rate, term and repayment frequency. The remaining household cash flow is NOT a lender assessment or an approved borrowing amount.

Enter your details

Proposed purchase price (NZ$)

Available deposit (NZ$)

Monthly household take-home income, after tax (NZ$)

Monthly household living costs, excluding existing debts and proposed loan (NZ$)

Monthly existing debt repayments (NZ$)

Assumed nominal annual interest rate (%)

Loan term (years)

Repayment frequency

Illustrative interest-rate increase (percentage points)

Your estimate

Illustrative principal-and-interest repayment—

Required home loan—

Equivalent monthly mortgage payment—

Estimated monthly cash flow left—

Loan-to-value ratio (LVR)—

Payment at stressed rate—

Cash flow left at stressed rate—

Enter valid figures for an indicative result.

Method and worked New Zealand example

Loan principal = property price − deposit. Repayments use standard amortisation at an unchanging nominal annual interest rate: payment = P × r/[1 − (1+r)⁻ⁿ], where r = annual interest rate ÷ payments per year and n = term in years × payment frequency.

Cash-flow estimate = entered monthly after-tax income − monthly living expenses − existing debt payments − equivalent monthly mortgage repayment. A $600,000, 30-year loan at 6% nominal interest repaid monthly is approximately $3,597.30 per month, excluding fees. Try a higher rate to see sensitivity.

Assumptions and important limitations

Not bank borrowing capacity or pre-approval. Does not reproduce any lender stress test or DTI rules. Excludes rates, insurance, buying costs, maintenance and fees unless already included in entered living expenses. Actual contracts can compound or calculate interest daily and change rates and payments.

Official sources (checked 11 October 2026): Reserve Bank DTI explainer; Consumer Protection borrowing money.

Frequently asked questions

Does a positive surplus mean my loan is approved?

No. Lenders assess serviceability, deposit, credit, existing debts and their own policies.

What is the LVR?

The loan divided by the property price, expressed as a percentage.

Why is this different from the mortgage repayment calculator?

This page compares household take-home cash flow and stress scenarios; the dedicated repayment page focuses on loan payments and payoff.