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Property · New Zealand

Borrowing power calculator NZ — guide and calculator

Explore an indicative loan range from household income, commitments and a test interest rate.

Guide reviewed 20 August 2026 · Interactive calculator in development

Calculator in development

Interactive calculator coming soon. Full guide available now.

KiwiTools is building and testing the borrowing power calculator. Everything below—the method, required information, worked example, assumptions, limitations and sources—is available now.

No estimated result is shown until the calculation is ready.

What this calculator will help with

The future result will be a transparent scenario only and will not imitate a particular bank credit decision.

Use the result to compare clearly defined scenarios rather than as a prediction. Keep every other input unchanged when testing one decision so the effect of that change remains visible.

How the calculation works

Available repayment capacity is estimated from entered income less expenses, debts and a buffer, then converted to a loan amount using an amortising-loan formula.

The finished calculator will show the assumptions beside the result and will not silently substitute a personal rate, price, eligibility decision or future forecast.

Information to collect before calculating

Using your own current figures will normally produce a more useful scenario than relying on a generic default. Prepare these inputs:

  1. 1

    Household income after relevant deductions

    Use a recent statement, bill, agreement, quote or measured figure where one is available. Keep the same basis when comparing alternatives.

  2. 2

    Living costs and existing debt commitments

    Use a recent statement, bill, agreement, quote or measured figure where one is available. Keep the same basis when comparing alternatives.

  3. 3

    Test rate, loan term and repayment buffer

    Use a recent statement, bill, agreement, quote or measured figure where one is available. Keep the same basis when comparing alternatives.

Worked example

Two households with the same income can receive different estimates when one enters higher debt repayments or living costs.

This example demonstrates the method only. It is not a recommended setting, current market quote or estimate for a particular person.

Assumptions and limitations

  • It is not pre-approval or lending advice
  • Banks use their own verified inputs, floors and credit policies

The finished tool will provide a general planning estimate, not financial, legal, tax, lending or eligibility advice. Confirm decisions with the relevant provider or authority.

How to interpret the future result

Read the result as an estimate produced from the values entered. Compare a realistic base case with a cautious alternative, and check which input causes the largest change.

A useful result should help frame the next question. It does not verify an application, contract, tax position, product suitability or future price.

A simple comparison process

  1. 01Enter a realistic base scenario using the best information available.
  2. 02Change one uncertain input to create a cautious second scenario.
  3. 03Confirm changeable rules, rates and quoted costs with the linked source or provider.

New Zealand sources

These primary and reputable sources provide context for the method. Changeable rates and rules will be checked again before the interactive calculator launches.

Frequently asked questions

Is the borrowing power calculator available yet?

The interactive calculator is still being built and tested. The method, inputs, example and limitations on this page are available now.

Will the result be exact?

No. It is not pre-approval or lending advice The finished calculator will show its assumptions and provide a planning estimate only.

Will this page address change when the calculator launches?

No. KiwiTools intends to add the calculator to this permanent page so saved links and the supporting guide remain in one place.

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