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ABS 2021 Census · Updated 21 May 2026
St Marys is a well-established middle-ring suburb of Adelaide, Australia, with a population of approximately 3,010, making it a boutique locality. Located approximately 9 km from the Adelaide CBD, St Marys is a middle ring area in South Australia. The median household income is $77,480 per year.
Moderate income levels in St Marys indicate steady rental demand from working households. Close CBD access strengthens tenant appeal and resale value.
Official Australia Post postcode for St Marys. 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 1 school within or near this suburb.
Find schools near St Marys on My School →Estimated 1 park 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.
3,010 residents places St Marys squarely in the middle of the South Australia suburb size distribution (state median 3,699), with market depth comparable to most SA localities. At $77,480/year, household income in St Marys is within 4% of the South Australia median ($80,964), placing the suburb firmly in the state's mainstream demographic band. Rent of $285/week (75% coverage of the $1,654/month median mortgage) leaves a gap of roughly $419/month that a typical investor bridges with negative gearing, depreciation and capital growth. At 9 km from the Adelaide CBD, St Marys sits inside the high-demand inner ring — properties here compete directly with the city's employment, transport and amenity networks.
This suburb suits long-term investors looking for a balance of rental yield and capital growth. Schools and transport underpin family demand. Local rents consume roughly 19% of household income — a useful sanity check on tenant affordability.
How St Marys stacks up against the median of all South Australia suburbs in our dataset. Positive values mean St Marys sits above the state median; negative means below.
| Metric | St Marys | SA median | Δ vs state |
|---|---|---|---|
| Population | 3,010 | 3,699 | -19% |
| Median household income | $77,480/yr | $80,964/yr | -4% |
| Median rent (weekly) | $285 | $320 | -11% |
| Median mortgage (monthly) | $1,654 | $1,616 | +2% |
| Distance to CBD | 9 km | 13 km | -31% |
| Separate houses | 63% | 73% | -10pp |
Pre-inspection briefing for St Marys — every item is derived from public datasets, with full citations in our data sources page.
Moderate buy-and-hold potential: St Marys's 3,010-person market and $77,480 median household income work for investors who are selective on street location and property quality rather than counting on a suburb-wide rerating.
Moderate rental coverage: rent of $285/week covers 75% of a $1,654/month mortgage, leaving a $419/month gap that an investor bridges with equity, depreciation and tax benefits.
Only 63% of dwellings are separate houses (vs 73% SA median) — this is a unit and townhouse market, where cosmetic flips struggle against body-corporate restrictions, thinner after-reno uplift and competing new supply.
Run the numbers on a St Marys property
Scenario comparison, cash flow analysis, tax modelling, and PDF export — all in one place.
Create free account →Capital-growth expectations for St Marys are modest for 2026 — incomes close to the SA median of $80,964 and a population of 3,010 suggest gains will lag headline metro markets. Rental coverage runs at ~75% of the typical mortgage ($1,235/month rent vs $1,654/month repayment), leaving a manageable top-up for most investors. The EquitySight investment score of 65/100 places St Marys in the upper-middle tier of Australian suburbs we profile, and overall investor sentiment is balanced heading into the second half of 2026.
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St Marys scores 65/100 on our EquitySight investment framework — a good rating. That score is driven by a population of 3,010, median household income of $77,480/year and median weekly rent of $285. 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 St Marys are proximity to Adelaide (9 km), a median household income of $77,480/year, a dwelling mix that is 63% separate houses, roughly 1 schools and 1 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.
St Marys has a usual resident population of approximately 3,010, compared with a South Australia suburb median of 3,699 — placing it in the lower 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.
St Marys sits 9 km straight-line from the Adelaide CBD. This is inner-ring territory — pricing competes directly with established Adelaide employment nodes.
The most recent census recorded a median weekly rent of $285 in St Marys, equating to approximately $14,820/year in gross rental income (state median $320/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 St Marys is $1,654, or approximately $19,848/year (vs $1,616/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 $285 works out to $1,235/month, covering 75% of the median mortgage repayment of $1,654/month. That leaves a $419/month shortfall (around $5,028/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 a thin buyer pool (3,010 residents), interest-rate sensitivity on the $1,654 median mortgage, the broader South Australia 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.