Population
Service age groups
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.
Related topics
Key insight
In 2021, Older workers and pre-retirees (50 to 59) was the most common category among residents in Castlecrag, accounting for 18.2% (539 people). This share was higher than Willoughby (C) (12.4%). Since 2016, the biggest change was in Older workers and pre-retirees (50 to 59), which increased by 496 people, while its share fell by 6.4 percentage points.
Section overview
Age structure - Service age groups
Castlecrag - Total persons (Usual residence)
This table summarises service age groups for Castlecrag in 2021 for persons, with comparison against Willoughby (C) and change since 2016.
Age structure - Service age groups snapshot
2021 distribution by category for Castlecrag, with comparison markers for Willoughby (C).
Babies and pre-schoolers (0 to 4)
2021 count
99
% of total
3.3%
Change from 2016
-0.1pp
99
3.3%
-0.1pp
Primary schoolers (5 to 11)
2021 count
265
% of total
8.9%
Change from 2016
-0.8pp
265
8.9%
-0.8pp
Secondary schoolers (12 to 17)
2021 count
367
% of total
12.4%
Change from 2016
+1.5pp
367
12.4%
+1.5pp
Tertiary education and independence (18 to 24)
2021 count
279
% of total
9.4%
Change from 2016
-0.9pp
279
9.4%
-0.9pp
Young workforce (25 to 34)
2021 count
125
% of total
4.2%
Change from 2016
+0.8pp
125
4.2%
+0.8pp
Parents and homebuilders (35 to 49)
2021 count
515
% of total
17.4%
Change from 2016
-2.0pp
515
17.4%
-2.0pp
Older workers and pre-retirees (50 to 59)
2021 count
539
% of total
18.2%
Change from 2016
-6.4pp
539
18.2%
-6.4pp
Empty nesters and retirees (60 to 69)
2021 count
391
% of total
13.2%
Change from 2016
+4.1pp
391
13.2%
+4.1pp
Seniors (70 to 84)
2021 count
334
% of total
11.3%
Change from 2016
+7.3pp
334
11.3%
+7.3pp
Elderly aged (85 and over)
2021 count
64
% of total
2.2%
Change from 2016
+2.2pp
64
2.2%
+2.2pp
Chart view
Age structure - Service age groups change
Absolute change in category counts between 2016 and 2021.
Babies and pre-schoolers (0 to 4)
+93
-0.1pp
Primary schoolers (5 to 11)
+248
-0.8pp
Secondary schoolers (12 to 17)
+348
+1.5pp
Tertiary education and independence (18 to 24)
+261
-0.9pp
Young workforce (25 to 34)
+119
+0.8pp
Parents and homebuilders (35 to 49)
+481
-2.0pp
Older workers and pre-retirees (50 to 59)
+496
-6.4pp
Empty nesters and retirees (60 to 69)
+375
+4.1pp
Seniors (70 to 84)
+327
+7.3pp
Elderly aged (85 and over)
+64
+2.2pp
Data table
Service age groups for Castlecrag. Age structure - Service age groups. 2021 and 2016 counts, percentages, and change compared with Willoughby (C).
| Category | 2021 | 2016 | Change | |||||
|---|---|---|---|---|---|---|---|---|
| Count | % | Willoughby (C)% | Count | % | Willoughby (C)% | Count | pp | |
| Babies and pre-schoolers (0 to 4) | 99 | 3.3% | 5.2% | 6 | 3.4% | 6.6% | +93 | -0.1pp |
| Primary schoolers (5 to 11) | 265 | 8.9% | 9.7% | 17 | 9.7% | 9.6% | +248 | -0.8pp |
| Secondary schoolers (12 to 17) | 367 | 12.4% | 7.6% | 19 | 10.9% | 6.4% | +348 | +1.5pp |
| Tertiary education and independence (18 to 24) | 279 | 9.4% | 7.2% | 18 | 10.3% | 8.1% | +261 | -0.9pp |
| Young workforce (25 to 34) | 125 | 4.2% | 12.4% | 6 | 3.4% | 15.2% | +119 | +0.8pp |
| Parents and homebuilders (35 to 49) | 515 | 17.4% | 24.5% | 34 | 19.4% | 23.9% | +481 | -2.0pp |
| Older workers and pre-retirees (50 to 59) | 539 | 18.2% | 12.4% | 43 | 24.6% | 11.7% | +496 | -6.4pp |
| Empty nesters and retirees (60 to 69) | 391 | 13.2% | 9.5% | 16 | 9.1% | 9.1% | +375 | +4.1pp |
| Seniors (70 to 84) | 334 | 11.3% | 8.9% | 7 | 4.0% | 7.0% | +327 | +7.3pp |
| Elderly aged (85 and over) | 64 | 2.2% | 2.6% | 0 | 0.0% | 2.3% | +64 | +2.2pp |
| Total | 2,965 | 100.0% | 100.0% | 175 | 100.0% | 100.0% | +2,790 | 0.0pp |