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ABS 2021 Census · Updated 21 May 2026
Thornleigh is a well-established middle-ring suburb of Sydney, Australia, with a population of approximately 8,898, making it a smaller community. Located approximately 20 km from the Sydney CBD, Thornleigh is a middle ring area in New South Wales. The median household income is $139,412 per year.
Strong household incomes in Thornleigh underpin solid property demand.
Official Australia Post postcode for Thornleigh. A postcode may cover multiple suburbs.
Australia Post Postcode Finder →Usual resident population at the most recent census.
Weekly median rent for occupied homes. Live rental data integration coming soon.
Annual median household income (before tax) across all households.
Straight-line distance from the suburb centroid to the nearest capital city CBD. Actual driving distance will be longer.
Estimated 2 schools within or near this suburb.
Find schools near Thornleigh on My School →Estimated 4 parks and green spaces near this suburb.
Monthly median mortgage repayment for households currently paying off a mortgage.
Proportion of separate houses versus units, townhouses, and other home types. Useful for investors assessing rental demand mix.
Thornleigh's population of 8,898 sits 67% above the New South Wales suburb median of 5,325, giving it a wider tenant and buyer catchment than the average NSW locality. Median household income of $139,412/year runs 43% above the New South Wales suburb median of $97,552, indicating strong purchasing power and the type of demographic profile that tends to sustain premium property prices through market cycles. Rent of $530/week (82% coverage of the $2,800/month median mortgage) leaves a gap of roughly $503/month that a typical investor bridges with negative gearing, depreciation and capital growth. 20 km from Sydney places Thornleigh in the middle commuter belt, close enough for daily trips by car or rail but at a materially lower price point than inner suburbs.
Middle-ring locations like this one historically reward patient holders — focus on homes near catchment-zone schools and major transport. Local rents consume roughly 20% of household income — a useful sanity check on tenant affordability.
How Thornleigh stacks up against the median of all New South Wales suburbs in our dataset. Positive values mean Thornleigh sits above the state median; negative means below.
| Metric | Thornleigh | NSW median | Δ vs state |
|---|---|---|---|
| Population | 8,898 | 5,325 | +67% |
| Median household income | $139,412/yr | $97,552/yr | +43% |
| Median rent (weekly) | $530 | $430 | +23% |
| Median mortgage (monthly) | $2,800 | $2,167 | +29% |
| Distance to CBD | 20 km | 45 km | -56% |
| Separate houses | 73% | 76% | -3pp |
Pre-inspection briefing for Thornleigh — every item is derived from public datasets, with full citations in our data sources page.
Strong buy-and-hold fundamentals: household incomes run 43% above the New South Wales suburb median ($139,412 vs $97,552), and the 20 km CBD distance keeps this suburb in the primary demand zone. In New South Wales, suburbs with this profile have historically clustered in the upper tercile of 10-year capital growth.
Moderate rental coverage: rent of $530/week covers 82% of a $2,800/month mortgage, leaving a $503/month gap that an investor bridges with equity, depreciation and tax benefits.
With 73% houses in a 8,898-person market, renovation margins depend on individual street and aspect rather than any suburb-wide story — do comparable-sales analysis before committing capital.
Run the numbers on a Thornleigh property
Scenario comparison, cash flow analysis, tax modelling, and PDF export — all in one place.
Create free account →Thornleigh enters 2026 with a demographic tailwind — household incomes 43% above the New South Wales suburb median of $97,552 and a population of 8,898 give it the depth and purchasing power to outperform the wider NSW market over the next 12–18 months. Rental coverage runs at ~82% of the typical mortgage ($2,297/month rent vs $2,800/month repayment), keeping cash flow in positive or near-neutral territory. The EquitySight investment score of 79/100 places Thornleigh in the upper-middle tier of Australian suburbs we profile, and overall investor sentiment is constructive heading into the second half of 2026.
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Thornleigh scores 79/100 on our EquitySight investment framework — a good rating. That score is driven by a population of 8,898, median household income of $139,412/year and median weekly rent of $530. Whether it fits your portfolio depends on whether you are targeting cash flow, capital growth, or a value-add renovation — all three are scored with suburb-specific numbers elsewhere on this page.
The main demand drivers in Thornleigh are proximity to Sydney (20 km), an above-state-median household income of $139,412/year, a dwelling mix that is 73% separate houses, roughly 2 schools and 4 parks within the catchment. Together these shape both owner-occupier and tenant demand and are the factors we weight most heavily in the suburb's investment score.
Thornleigh has a usual resident population of approximately 8,898, compared with a New South Wales suburb median of 5,325 — placing it in the upper half of the state's suburbs by size. Population is the clearest proxy for market depth: more residents mean more transactions and typically a shorter average days-on-market on resale.
Thornleigh sits 20 km straight-line from the Sydney CBD. This is comfortable commuter territory, with reasonable rail and road access to the city.
The most recent census recorded a median weekly rent of $530 in Thornleigh, equating to approximately $27,560/year in gross rental income (state median $430/week). Market rents have typically drifted above the recorded figure — verify against current listings on realestate.com.au and Domain before making an offer.
The median monthly mortgage repayment in Thornleigh is $2,800, or approximately $33,600/year (vs $2,167/month state median). Stress-test your own borrowing at rates 1–2 percentage points above today's to make sure you can still service the loan through an RBA tightening cycle.
A median weekly rent of $530 works out to $2,297/month, covering 82% of the median mortgage repayment of $2,800/month. That leaves a $503/month shortfall (around $6,036/year before tax benefits), so a typical owner-occupier-priced property here is negatively geared. Actual cash flow depends on your deposit, loan terms, ownership costs and marginal tax rate — run the full numbers in our rental yield calculator.
The main risks are interest-rate sensitivity on the $2,800 median mortgage, the broader New South Wales market cycle. Each of these is covered in the Risk Factors section above with suburb-specific numbers rather than generic warnings.
Every number on this page comes from the ABS 2021 Census of Population and Housing, Australia Post postcode reference data, and OpenStreetMap amenity tiles. The investment score, strategy verdicts, and comparison table are computed deterministically from those inputs — no opinion, no estimation. See our full methodology and the data sources and licences for the formulas we use.