Underdale (SA)

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According to investigations of ABS population estimates for the region, alongside newly confirmed address points from Districts following the Census, the suburb of Underdale has a population estimated to be 3,176 in May 2026. This represents a growth of 747 individuals (30.8%) relative to the 2,429 residents counted during the 2021 Census. This population shift is calculated from the estimated resident figure of 3,176, derived by Districts through analysing the ABS ERP data from June 2025 together with 34 newly validated addresses since the Census. Such a population count corresponds to a density of 3,113 persons per square kilometer, placing the suburb in the highest quarter of all Australian locations evaluated by Districts. The 30.8% expansion rate in the suburb of Underdale since the 2021 Census outpaced the state growth of 7.5% and the local SA3 region, positioning the locality as a regional leader in expansion. The population gains were heavily supported by overseas arrivals, who accounted for roughly of the overall growth in recent times.

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The suburb of Underdale is characterized by an educated labor force, a strong showing in basic services, an unemployment rate of only 2.6%, and estimated job numbers increasing by 12.0% over the past year, according to Districts regional data. In March 2026, there were 1,953 employed locals, the unemployment level sat 1.2% lower than the 3.8% recorded in Greater Adelaide, and the labor force participation rate reached an elevated 74.1% compared to 66.6% across Greater Adelaide. According to Census replies, a small share of 11.3% of workers operated from home, though this may have been influenced by pandemic-related movement restrictions.

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The suburb of Underdale has an income level that aligns closely with the national average, according to ATO figures compiled by Districts for financial year 2023. The median tax returns in the suburb of Underdale were $53,661 and average earnings were $67,028, compared to regional medians of $54,808 and averages of $66,852 in Greater Adelaide. Accounting for a 10.17% rise in the Wage Price Index since financial year 2023, local values are estimated at approximately $59,118 for the median and $73,845 for the average as of March 2026. According to the Census, household, family, and individual incomes are moderate in the suburb of Underdale, placing between the 40th and 55th percentiles. Distribution statistics show the dominant income band is the $1,500 - 2,999 category, containing 30.3% of locals (962 people), matching the regional rate of . Affordability pressures are high, with residents retaining just of their income, which sits in the st percentile, while the SEIFA index ranks the area in the th decile for income.

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Housing types in the suburb of Underdale at the recent Census consisted of 63.6% detached houses and 36.5% alternative dwellings including apartments, semi-detached, and other types, compared to 75.2% detached houses and 24.9% alternative dwellings in Greater Adelaide. Home ownership rates in the suburb of Underdale matched the Adelaide metro benchmark of 31.1%, with remaining properties held under a mortgage (31.1%) or occupied by renters (37.9%). The median monthly home loan payment was $1,786, which is higher than the Adelaide metro average of $1,562, while the weekly rent median was $310 compared to the Adelaide metro average of $320. Nationally, mortgage costs in the suburb of Underdale are below the Australian average of $1,863, and typical rent costs are much lower than the national median of $375.

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Families represent the primary household type at 62.4%, consisting of couples raising children at 28.2%, couples without children at 24.2%, and single parents with children at 8.7%. Non-family households comprise the remaining 37.6% of homes, consisting of single-person households at 31.9% and shared group households at 5.4%. The median household size of 2.3 people is smaller than the Greater Adelaide average of 2.5.

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The educational makeup of the area is distinct in the region, with higher education qualification rates showing 35.6% of residents aged 15+ holding a degree, compared to the SA average of 25.7% and the Greater Adelaide average of 28.9%. Bachelor programs represent the most common degree at 23.9%, followed by postgraduate study at 9.2% and graduate diplomas at 2.5%. Practical and vocational qualifications are also common, with 28.9% of residents aged 15+ holding trade credentials, consisting of advanced diplomas at 10.7% and certificates at 18.2%.

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Public transit statistics show 14 active stops operating in the suburb of Underdale, consisting of bus services. These stops are served by 24 unique routes, which provide a total of 1,682 passenger trips each week. Access to transit is rated as excellent, with locals living an average of 153 meters from their closest stop. Being a mostly residential suburb, the majority of working residents travel outside the area, with private cars remaining the primary travel mode at 81%, and buses used by 9%. Households own an average of 1.3 cars. A small proportion of 11.3% of workers worked from home, based on the 2021 Census, which may have been impacted by pandemic restrictions.

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Assessments of local health statistics point to strong well-being outcomes throughout the suburb of Underdale, with Districts analysis of mortality rates and chronic health conditions showing low rates of common illnesses across younger and older demographics, while the share of residents with private health insurance is just ahead of the typical SA2 area at approximately 53% of the population, representing about 1,698 individuals.

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The suburb of Underdale registers high cultural diversity, with 33.6% of the local population born overseas and 35.5% using a non-English language at home. Christianity is the primary religion, followed by 49.6% of residents in the suburb of Underdale. The most pronounced difference is in the Other religious category, which represents 3.9% of the local population compared to 1.8% across Greater Adelaide.

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With a median age of 38, the suburb of Underdale is close to the Greater Adelaide figure of 39 and identical to the national average of 38 years. Relative to Greater Adelaide, the 25 - 34 cohort is highly represented at 16.9% locally, while children aged 5 - 14 are less common at 9.9%. Since 2021, the 65 to 74 age group rose from 8.9% to 9.9% of the population, while the 55 to 64 group decreased from 13.3% to 11.6%. Modeling suggests that by 2041, the local age structure will change, with the 45 to 54 cohort projected to increase by 80 people () from to while the to group is projected to decrease by residents.

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Underdale currently has an estimated 184 children under 5 years old, comprising approximately 102 children aged 0-2 and 68 children aged 3-4. This cohort grew by an estimated 46% since the previous census. though population forecasts indicate future decline, with an anticipated decrease of 3% by 2041 (to approximately 179 children). Meanwhile the 5-12 cohort currently amounts to 262. While growth has been positive birth rates observed in the area have been moderate, with approximately 9.1 births per 1,000 residents recorded over the latest two-year period analysed which ranks the area within the middle tier nationally. This rate has slowed down slightly in recent years however.