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South Australia · Postcode 5255
Mount Observation postcode and suburb data
South Australia · Phone area code 08 · 49 km from Adelaide
Suburb snapshot
Mount Observation at a glance vs SA
Fast facts and benchmark bars show the suburb's key postcode, Census, SEIFA, school and LGA signals in context.
Quick facts
Benchmarks against SA
Income, rent and SEIFA figures are from the ABS 2021 Census and are reported in 2021 dollars, not adjusted for subsequent inflation.
Where Mount Observation ranks: household income is in the top 10% of SA suburbs.
ABS Census 2021 · SEIFA 2021Detailed comparison table
Mount Observation vs the SA average and the national average, using population-weighted 2021 Census data.
| Metric | Mount Observation | SA avg | AU avg | Greater Adelaide |
|---|---|---|---|---|
| Household income/wk | $2,250 +SA | $1,545 | $1,836 | $1,620 |
| Mortgage/month | $2,383 +SA | $1,558 | $1,958 | $1,666 |
| Median age | 39 | 45.0 | 45.0 | 42.0 |
| SEIFA decile | 6/10 ≈SA | 5.0/10 | 6.0/10 | 7.0/10 |
| Unemployment | 0.0% -SA | 6.0% | 5.0% | 6.0% |
Green pill = at least 10% above the SA average; red = at least 10% below; grey = within 10%. For unemployment, colour polarity is inverted: lower is better.
Mount Observation is a locality 49 km from Adelaide in South Australia, classified as inner regional by the ABS. The postcode is 5255. It falls within the South Australia - South East region. The local government area is Alexandrina.
According to the 2021 Census, Mount Observation has a population of 10 with a median age of 39. The median weekly household income is $2,250, above the SA average.
Housing in Mount Observation includes a median monthly mortgage repayment of $2,383, 3 total dwellings. These housing costs sit above the SA average.
On the SEIFA Index of Relative Socio-economic Advantage and Disadvantage, Mount Observation scores in decile 6 out of 10, which is around the national average.
Mount Observation is part of the Murray and Mallee statistical area in South Australia.
Mount Observation details
Location, Census, housing, SEIFA and geography fields used across this profile.
| Postcode | 5255 |
| State | South Australia (SA) |
| Phone Area Code | 08 |
| Population (2021) | 10 |
| Median Age | 39 years |
| Median Household Income (Census 2021) | $2,250/week |
| Median Personal Income (Census 2021) | $1,125/week |
| Median Monthly Mortgage (Census 2021) | $2,383 |
| Average Household Size | 3.5 persons |
| Area | 9.4 km² |
| Population Density | 1/km² |
| Total Dwellings | 3 |
| Australian Citizens | 90.0% |
| Unemployment Rate | 0.0% |
| SEIFA IRSAD Decile | 6/10 (average) |
| Latitude | -35.3516869 |
| Longitude | 138.7542899 |
| Distance from Adelaide | 49 km |
| Region (SA4) | South Australia - South East |
| Area (SA3) | Murray and Mallee |
| Local Government | Alexandrina |
| Federal Electorate | Mayo |
| State Electorate | Hammond |
| Time Zone | ACST (UTC+9:30), Australia/Adelaide (standard time) |
Age Profile
Show counts
| 0–14 years | 3 (30.0%) |
| 15–24 years | 0 (0.0%) |
| 25–44 years | 4 (40.0%) |
| 45–64 years | 0 (0.0%) |
| 65+ years | 0 (0.0%) |
SEIFA socio-economic index
Motor Vehicles per Dwelling
| No vehicle | 0 (0.0%) |
| 1 vehicle | 0 (0.0%) |
| 2 vehicles | 3 (100.0%) |
| 3+ vehicles | 0 (0.0%) |
Suburbs Near Mount Observation
Same Postcode (5255)
More Mount Observation Data
Page last reviewed . Data sources: Australian Bureau of Statistics 2021 Census (CC BY 4.0), SEIFA 2021 IRSAD, ACARA school profiles 2025. How this data is sourced.