How our data and calculations work

weekly_rent_budget = annual_income × 0.30 ÷ 52

A household is considered in rental stress when it spends more than 30% of gross income on rent, the standard AIHW/Treasury definition. Suburbs where the median rent is below your budget are "affordable"; 30–40% of income is "tight"; above 40% is "out of reach". You can override the 30% default with a custom budget.

Worked example: On $80,000: 80,000 × 0.30 ÷ 52 = $461.54/week.

M = P·r(1+r)ⁿ ÷ ((1+r)ⁿ − 1)   where P = price − deposit, r = rate÷12, n = months

The standard principal-and-interest amortisation identity every lender uses. The map assumes a 20% deposit and 25-year term; the repayments calculator lets you set all three inputs. Weekly and fortnightly figures are monthly × 12 ÷ 52 and × 12 ÷ 26. LMI is flagged when the deposit falls below 20%.

Worked example: $600,000 home, 20% deposit, 5.85% over 25 years: P = $480,000 → ≈ $3,046/month. Affordable (≤30% of gross) on incomes above ≈ $121,800.

assessment_rate = max(your_rate + 3%, 5.5%)   ·   capacity = loan serviceable by your net surplus at that rate

We estimate net income from ATO brackets, subtract declared liabilities (credit cards count at 3.8% of the limit per month, rental income is haircut to 80%) and HEM-style living expenses, then solve for the loan whose repayment your monthly surplus can service at the assessment rate.

Worked example: At a 6.0% headline rate you are assessed at 9.0%, the APRA buffer is why capacity sits well below what the advertised rate implies.

duty = state_bracket_schedule(price) − FHB_concessions (+ foreign surcharge if applicable)

All eight state and territory progressive schedules are implemented, including current first home buyer concessions (each verified against its revenue office between July and October 2026) and foreign-buyer surcharges. We update when state budgets change the rates, each schedule's effective date is on the Data Sources page.

Worked example: NSW first home buyer at $850,000: above the $800k full exemption, so the tapered concession to $1M applies.

premium ≈ loan × band_rate(LVR, loan_size) × 1.1

LMI applies above 80% LVR. Rates come from standard industry band tables keyed on LVR and loan size; the ×1.1 approximates the ~10% duty most states levy on the premium itself. Actual quotes vary by insurer, treat ours as a guide.

Worked example: A $570,000 loan on a $600,000 home is 95% LVR, a materially higher premium band than 85%.

compare Σ renting_costs  vs  Σ ownership_costs − equity_built, over your horizon

Renting totals your rent with annual growth. Owning totals repayments, rates, maintenance and transaction costs, minus the equity you build from principal reduction and price growth at the rates you set. The verdict is whichever path leaves you ahead.

Worked example: Short horizons usually favour renting: stamp duty and legals are front-loaded, while equity builds slowly at first.

break_even_months = switching_costs ÷ monthly_saving

Monthly saving is your current repayment minus the repayment at the new rate over the remaining term (we don't restart the clock). Discharge, application and valuation fees, plus any fixed-rate break cost you enter, make up the switching costs.

Worked example: $1,050 in switch costs against a $210/month saving → break-even in 5 months.

tax_effect = tax(income) − tax(income − rental_loss) + Medicare   ·   CGT = tax(income + taxable_gain) − tax(income) + Medicare, taxable_gain = 50% of (sale − cost base) when the sale contract is more than 12 months after the purchase contract; cost base = purchase price + costs of buying and selling + capital improvements

Rental losses offset other income at your marginal rate using current ATO resident brackets. Gains on assets held over 12 months receive the 50% individual discount. Assumes individual ownership: company, trust and SMSF structures differ.

Worked example: A $10,000 rental loss on a $150,000 income returns $3,900 (37% tax plus 2% Medicare). A $200,000 gain held more than 12 months adds $100,000 to taxable income: on a $120,000 salary that is $40,350 of tax.

ATO 2026-27 resident brackets + 2% Medicare levy (reduced below the low-income threshold) + HELP 2026-27 repayment schedule

Take-home income uses the 2026-27 brackets: the lowest rate is 15% from 1 July 2026. The Medicare levy uses the low-income reduction for a single person. HELP repayments use the marginal schedule in place since 1 July 2025: nil to $69,528 of repayment income, then 15c, then 17c for each dollar, and 10% of the whole income from $186,051. We do not model offsets (LITO) or deductions, so lower-income take-home figures are slightly conservative. Updated each financial year.

months_to_save = deposit_required ÷ monthly_savings

Deliberately conservative: no compounding on savings. First Home Super Saver Scheme contributions can meaningfully shorten the timeline via concessional tax treatment.