How the Atlas is built.
The Community Atlas is built from the 2021 Australian Census of Population and Housing. This page explains what is in it, how the numbers are calculated, and — just as importantly — what it does not capture. This is a living document; the methodology page will grow as the Atlas grows.
Every number on the Atlas traces back to ABS Census 2021, the authoritative enumeration of every Australian on census night. Language-at-home, ancestry, and country-of-birth counts are aggregated from SA1 (the smallest published unit) up through suburb (SAL), local government area (LGA), state and national totals.
We use the ABS's own geographic concordances to map between levels. Where the ABS suppresses small counts for privacy, the Atlas shows the suppressed value as recorded.
The census is a snapshot, and snapshots miss things. Newly arrived communities are systematically under-counted because enumeration depends on households being contactable in English. Temporary migrants, asylum seekers and mobile populations are particularly poorly represented.
Language-at-home is also a single question: it does not measure proficiency, literacy, or preference for receiving written vs spoken information. A community can appear small in the Atlas and still be the right audience for a translation.
The Atlas is refreshed against the latest ABS release (currently Census 2021, updated April 2026). When Census 2026 data is released we will re-run the full pipeline and mark any change of ≥5% in headline figures with a trend indicator.
If a number on the Atlas disagrees with your records, or a community you serve is missing or misrepresented, tell us. This is a public good and it gets better when the people it describes correct it.