Population
Service age groups
Service age groups divide the population into broad life-stage bands such as children, young adults, working-age adults, and older people. The groupings are designed to reflect typical demand for age-based services and facilities rather than exact five-year cohorts.
Related topics
About this topic
Service age groups divide the population into broad life-stage bands such as children, young adults, working-age adults, and older people. The groupings are designed to reflect typical demand for age-based services and facilities rather than exact five-year cohorts.
This view is useful for planning childcare, schools, recreation, aged services, and other community infrastructure. It works best alongside five year age groups, household type, and dwelling data, which add more detail about who is living in an area and how needs may change over time.
Interpretation notes
- This is a derived grouping rather than a direct Census question, so the age bands are planning-oriented summaries built from standard age data.
- Percentages relate to the total population; use five year age groups when exact cohort detail matters.
Key insight
In 2021, Mid-life adults (35 to 49) was the most common category among residents in Willoughby (C), accounting for 24.5% (18,556 people). This share was higher than Greater Sydney (21.5%). Since 2016, the biggest change was in Early career adults (25 to 34), which decreased by 1,949 people and 2.8 percentage points.
Section overview
Age structure - Service age groups
Willoughby (C) - Total persons (Usual residence)
This table summarises service age groups for Willoughby (C) in 2021 for persons, with comparison against Greater Sydney and change since 2016.
Chart view
Age structure - Service age groups snapshot
2021 distribution by category for Willoughby (C), with comparison markers for Greater Sydney.
Early childhood (0 to 4)
Primary school age (5 to 11)
Secondary school age (12 to 17)
Young adults (18 to 24)
Early career adults (25 to 34)
Mid-life adults (35 to 49)
Pre-retirement adults (50 to 59)
Retirement transition (60 to 69)
Established seniors (70 to 84)
Advanced age (85 years and over)
Age structure - Service age groups change
Absolute change in category counts between 2016 and 2021.
Early childhood (0 to 4)
-947
-1.4pp
Primary school age (5 to 11)
+163
+0.1pp
Secondary school age (12 to 17)
+965
+1.2pp
Young adults (18 to 24)
-625
-0.9pp
Early career adults (25 to 34)
-1,949
-2.8pp
Mid-life adults (35 to 49)
+819
+0.6pp
Pre-retirement adults (50 to 59)
+736
+0.7pp
Retirement transition (60 to 69)
+381
+0.4pp
Established seniors (70 to 84)
+1,517
+1.9pp
Advanced age (85 years and over)
+226
+0.3pp
Data table
Service age groups for Willoughby (C). Age structure - Service age groups. 2021 and 2016 counts, percentages, and change compared with Greater Sydney.
| Category | 2021 | 2016 | Change | |||||
|---|---|---|---|---|---|---|---|---|
| Count | % | Greater Sydney% | Count | % | Greater Sydney% | Count | pp | |
| Early childhood (0 to 4) | 3,954 | 5.2% | 6.0% | 4,901 | 6.6% | 6.4% | -947 | -1.4pp |
| Primary school age (5 to 11) | 7,314 | 9.7% | 8.8% | 7,151 | 9.6% | 8.8% | +163 | +0.1pp |
| Secondary school age (12 to 17) | 5,734 | 7.6% | 7.1% | 4,769 | 6.4% | 6.9% | +965 | +1.2pp |
| Young adults (18 to 24) | 5,424 | 7.2% | 8.8% | 6,049 | 8.1% | 9.6% | -625 | -0.9pp |
| Early career adults (25 to 34) | 9,373 | 12.4% | 15.5% | 11,322 | 15.2% | 16.1% | -1,949 | -2.8pp |
| Mid-life adults (35 to 49) | 18,556 | 24.5% | 21.5% | 17,737 | 23.9% | 21.1% | +819 | +0.6pp |
| Pre-retirement adults (50 to 59) | 9,408 | 12.4% | 12.0% | 8,672 | 11.7% | 12.2% | +736 | +0.7pp |
| Retirement transition (60 to 69) | 7,152 | 9.5% | 9.8% | 6,771 | 9.1% | 9.5% | +381 | +0.4pp |
| Established seniors (70 to 84) | 6,719 | 8.9% | 8.7% | 5,202 | 7.0% | 7.5% | +1,517 | +1.9pp |
| Advanced age (85 years and over) | 1,959 | 2.6% | 2.0% | 1,733 | 2.3% | 2.0% | +226 | +0.3pp |
| Total | 75,613 | 100.0% | 100.0% | 74,302 | 100.0% | 100.0% | +1,311 | 0.0pp |