The Finance Algorithm
§ Tool · tier 3 · independent

Affordability Stress Tester.

Test your loan against rate rises, income drops, and life changes

AI advisorFree, no signupOn-deviceupd May 2026
Inputs
Your numbers
$
$600k
%
6.5%
30
$
$8k
$
$4k
$
$20k

Math updates live as you change inputs · AI runs on submit

Awaiting inputs

Move the sliders or type in the form on the left — the math updates live as you go. Click Get AI verdict when you want a written analysis.

What happens if rates rise 2%? What if you lose your job for 3 months? What about having a baby? Our stress tester simulates these scenarios so you know your limits BEFORE you commit.

§ Worked examples

Real-world scenarios

Rate Rise Scenario

The Chens have $7,500 monthly income, $520,000 loan at 6.2%. They want to know if they can handle rates at 8%.

Inputs

loanAmount:520,000interestRate:6.2loanTerm:28householdIncome:7,500monthlyExpenses:3,200emergencyFund:25,000

Current repayment: $3,050. At 8%: $3,680 (+$630). After expenses, buffer reduces from $1,250 to $620/month. Tight but manageable with emergency fund.

Income Drop Scenario

Maria earns $9,000/month but wants to know if she could handle dropping to $6,500 during parental leave.

Inputs

loanAmount:480,000interestRate:6.5loanTerm:30householdIncome:9,000monthlyExpenses:2,800emergencyFund:40,000

At $9,000 income: $3,170 buffer. At $6,500: -$330 shortfall. Would need to draw $330/month from savings. 40k fund covers 10 months of shortfall.

§ FAQ

Questions Australians ask

§ Glossary

Plain-English definitions

Mortgage Stress
When housing costs exceed 30% of household income. At 40%+, you're in 'severe mortgage stress' with limited capacity to handle shocks.
Buffer Rate
The additional interest rate (usually 3%) that lenders add when assessing your ability to repay, ensuring you can handle rate rises.
DTI (Debt-to-Income) Ratio
Your total debts divided by annual income. Lenders typically cap this at 6-7x, but lower is more comfortable for you.