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Debt to Income (DTI) Calculator

​Our calculator shows your debt-to-income ratio and how it compares against New Zealand's lending rules
Updated 2 August 2026
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​Summary
  • Many borrowers who stretched to buy a property with minimal deposits are now sitting on debt that exceeds the value of their home.
  • Debt-to-income (DTI) ratios are among the main tests banks use when deciding how much to lend.
  • Your DTI is your total lending divided by your gross (before-tax) annual income. For example, a DTI of 5 means you owe five times what you earn in a year - someone with a mortgage of $500,000 earning $100,000 would have a DTI of 5.

Know This First: From 1 July 2024, the Reserve Bank's DTI rules allow banks to make only 20% of new owner-occupier lending to borrowers with a DTI above 6, and only 20% of new investor lending with a DTI above 7.

This means that most lending has to sit under those thresholds. If your DTI is above the limit, you are competing for a small, tightly managed slice of each bank's lending, and you will usually need strong income, a large deposit or other factors in your favour.

Related Reading: ​Our Debt-to-Income (DTI) ratios guide explains what they mean, how they influence your home loan prospects, ways to enhance your ratio and must-know facts and frequently asked questions. 

Calculate your DTI

Enter gross annual figures - the calculator uses conservative bank assumptions by default.

Gross annual income
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$
$
$
Rental income counted by the bank75%
Most banks count only part of rental income to allow for vacancy, rates, insurance and management. 75% is a conservative starting point.
Existing debt
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$
$
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New lending you're considering (optional)
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Important - Two things catch people out:
  1. First, banks count your full credit card and overdraft limit as debt, not what you currently owe, so a $10,000 card you never use still counts as $10,000 of debt. Reducing or closing limits you don't need is one of the fastest ways to improve your position.
  2. Second, rental income is discounted, often to around 75%, to allow for vacancy and running costs, so a property earning $30,000 a year may only add around $22,500 to the income the bank counts.

How the DTI rules work
The Reserve Bank does not ban high-DTI lending outright - instead, it sets "speed limits":
  • Banks can lend above a DTI of 6 to owner-occupiers and above 7 to investors, but only for up to 20% of their new lending in each category. The other 80% must sit at or below those thresholds.
  • In practice, this means a DTI of 6 or less (owner-occupier) or 7 or less (investor) gives you the widest choice of lenders and the smoothest path to approval. Above the threshold, you are not automatically declined, but you are competing for a limited pool, and banks reserve it for the borrowers they see as the lowest risk.
  • DTI and Serviceability are two different tests, and you have to pass both - DTI caps the size of the loan relative to your income, while Serviceability checks whether you can afford the repayments. Banks test this at an interest rate well above the current rate, often around 8% or more.
  • It is entirely possible to sit comfortably under the DTI threshold and still be declined because the repayments do not stack up at the stressed rate.​
Our View:
  • Treat the number this calculator gives you as a ceiling on what the rules allow, not a target to aim for.
  • The amount you can comfortably repay through a period of higher rates or a drop in income is almost always the more important figure.
  • Borrowing to the very limit a bank will allow leaves no room for the things that go wrong, and over a 30-year loan, something always does.
  • The borrowers who sleep at night are the ones who left themselves a buffer, not the ones who borrowed up to the limits.


How to improve your DTI
You have two options - reduce debt and/or increase income.
  • Clearing or reducing high-limit credit cards, paying down car and personal loans, and closing unused overdraft and BNPL facilities all lower the top of the ratio.
  • On the income side, a pay rise, a second income on the application, or for the self-employed, a stronger two-year average of earnings, all help. The calculator above shows you exactly how much borrowing room each debt is costing you.
Related Resources: