Debt-to-Income Ratio: What to Check Before You Trust the Number

Updated 6 August 2026 · Loans and credit

A Debt-to-Income Ratio Calculator gives a fast answer, but the answer is only as good as what goes in. These are the mistakes we see most often with Debt-to-Income ratio calculations in Australia, and how to avoid them.

1. Paying only the minimum

Minimum repayments on credit cards can take decades and cost more than the original balance.

2. Ignoring fees

Establishment, monthly and early repayment fees can outweigh a lower interest rate.

3. Not planning for a balloon payment

A balloon lowers repayments now but leaves a large lump sum to pay or refinance later.

4. Focusing on the monthly repayment

A longer term lowers repayments but raises total interest. Look at the total cost.

5. Overlooking the detail that matters most here

APRA monitors lending at six times income or more, and many lenders cap or scrutinise loans above that level.

How the debt-to-income ratio changes with gross annual income

A common mistake is getting one input slightly wrong. Here is what happens to the debt-to-income ratio when “Gross annual income ($)” is off by up to 20% in either direction, with everything else held steady.

Gross annual income ($)	Debt-to-income ratio
88,000	5.11x
99,000	4.55x
110,000	4.09x
121,000	3.72x
132,000	3.41x

At 88,000 the result is 5.11x; at 132,000 it is 3.41x. If a small change in this input moves the answer a lot, it is worth double-checking that figure before you rely on the result.

A quick sense check

DTI = total debt ÷ gross annual income. With typical inputs the calculator returns debt-to-income ratio of 4.09x. If your own result looks wildly different, check that each figure is in the right unit and period (weekly, monthly or yearly) before drawing conclusions.