# How CensusAtlas works Most figures on CensusAtlas come from the Australian Bureau of Statistics (ABS) Census; we also layer in other open datasets (listed below) for economic, education and climate context. This page explains where the data comes from, how the shares, medians and trends are calculated, and the caveats worth knowing before you cite a number. ## Where the data comes from All figures are sourced from the Australian Bureau of Statistics (ABS) Census of Population and Housing, used under CC BY 4.0. We use the published ABS DataPacks: the 2011 Basic Community Profile (the "B" tables) and the 2016 and 2021 General Community Profile (the "G" tables). CensusAtlas is an independent project and is not affiliated with, nor endorsed by, the ABS. The ABS renumbered several tables between 2016 and 2021 (the 2021 release inserted new health tables, shifting the later table numbers), so a table number alone is not stable across years. We match cells by their full ABS description rather than by table number, so a statistic refers to the same concept in every census it appears in. ## How we calculate shares A "share" (for example, the share of people renting) is a numerator divided by a denominator drawn from the same Census table — renting households over all households, say — expressed as a percentage. To keep small areas honest we apply a small-denominator suppression rule: where the denominator is fewer than 20 people (or dwellings/families) the share is withheld rather than shown. The ABS adds small random adjustments to protect confidentiality, and on a tiny base those adjustments can swing a percentage wildly, so a suppressed share is more honest than a noisy one. ## Medians and averages For medians and averages (median rent, median age, average household size), a reported value of zero almost always means "not applicable" rather than a genuine $0 or 0 years — for instance, median rent where nobody rents. We therefore treat a zero median or average as no data and leave it blank, so it never drags down a map's colour scale or a ranking. ## Comparing 2011 and 2016 with 2021 Statistical area boundaries are redrawn at each census, so the 2011 and 2016 figures can't be laid directly over the 2021 map. We re-aggregate the older years onto 2021 boundaries using the ABS ASGS correspondences: - **Counts** (people, dwellings) are apportioned to each 2021 area in proportion to the correspondence ratio and summed. - **Medians and averages** can't be added up, so we carry the older value across only where a single 2021 area accounts for most of the old area (a correspondence ratio of at least 60%). A few statistics changed definition between censuses (or are new in 2021). Those are flagged as not directly comparable on the page, and we drop the change-since callout rather than imply a trend that isn't real. ## Other open datasets Alongside the Census, CensusAtlas layers in other open datasets to describe what a place is like — its socio-economic profile, population growth, the local economy, schools and climate. Each is CC BY 4.0, aligned to 2021 ABS boundaries and carries its own vintage, so it is never confused with Census counts. - **Socio-Economic Indexes for Areas (SEIFA)** — Australian Bureau of Statistics (2021), https://www.abs.gov.au/statistics/people/people-and-communities/socio-economic-indexes-areas-seifa-australia/latest-release, CC BY 4.0. - **Regional Population (Estimated Resident Population)** — Australian Bureau of Statistics (2024), https://www.abs.gov.au/statistics/people/population/regional-population/latest-release, CC BY 4.0. - **Counts of Australian Businesses & Building Approvals** — Australian Bureau of Statistics (2025), https://www.abs.gov.au/statistics/economy/business-indicators/counts-australian-businesses-including-entries-and-exits/latest-release, CC BY 4.0. - **Australian Schools List** — Australian Curriculum, Assessment and Reporting Authority (ACARA) (2025), https://www.acara.edu.au/contact-us/acara-data-access, CC BY 4.0. - **SILO gridded climate data** — Queensland Government (Long Paddock) (2019–2023), https://www.longpaddock.qld.gov.au/silo/, CC BY 4.0. - **Public transport timetables (GTFS)** — State & territory transport agencies (2026), https://www.transit.land/feeds?adm0_name=Australia, CC BY 4.0 (WA: custom PTA licence). - **Road & path network (OpenStreetMap, via Valhalla)** — OpenStreetMap contributors (2026), https://www.openstreetmap.org/copyright, ODbL 1.0. - **Transit accessibility (GTFS + OpenStreetMap, via R5)** — State transport agencies & OpenStreetMap contributors (2026), https://www.openstreetmap.org/copyright, ODbL 1.0 + CC BY. - **Recorded crime statistics** — State & territory police services and crime statistics agencies (2025), https://www.abs.gov.au/statistics/people/crime-and-justice, CC BY 4.0 (WA: CC BY-NC 4.0). - **Walkability (OpenStreetMap, GTFS, ACARA & G-NAF, via Valhalla)** — OpenStreetMap contributors, state transport agencies, ACARA & Geoscape Australia (2026), https://www.openstreetmap.org/copyright, ODbL 1.0 + CC BY. - **Geocoded National Address File (G-NAF Core)** — Geoscape Australia (via data.gov.au) (May 2026), https://data.gov.au/dataset/geocoded-national-address-file-g-naf, CC BY 4.0 (Geoscape G-NAF end-user licence). - **SRTM 1-arc-second digital elevation model** — NASA / U.S. Geological Survey (via AWS Terrain Tiles) (SRTM v3), https://registry.opendata.aws/terrain-tiles/, Public domain — "SRTM data courtesy of the U.S. Geological Survey". Climate figures are sampled from the SILO ~5 km gridded record at each area's centroid; at that resolution read them as estimates for larger areas (SA3/LGA) rather than precise values for small urban SA2s. **Map basemap.** The roads, water and place labels beneath the choropleth come from OpenStreetMap, rendered into our own muted vector style (built with planetiler on the OpenMapTiles schema). OpenStreetMap data is ODbL; it is used only as on-screen map context. **Recorded crime** has no national sub-state source, so it is stitched from each state/territory police service (NSW BOCSAR, Victoria Crime Statistics Agency, Queensland Police Service, SA Police, ACT Policing) and harmonised to ANZSOC-aligned offence groups (assault, sexual offences, robbery, burglary, theft, motor vehicle theft, property damage, drug offences). The headline figure is the recorded-offence rate per 100,000 residents, computed consistently against each area's 2021 Census usual-resident population — so the latest crime year post-dates that base, and areas with large daytime/visitor populations (CBDs) read high per resident (rates below a small population floor are withheld). Offence definitions differ between states, so cross-state comparisons are indicative only and rankings default to within a state. The full annual series (from 2000) sits behind each area's trend. Coverage is not yet national: WA (police-district geography), NT (multi-area aggregates) and Tasmania (no machine-readable sub-state data) are not included; drug offences are not published in the SA or ACT releases. ## Measures we derive ourselves A few measures are not published by anyone, so CensusAtlas builds them from open data to put every place on the same basis. This is what they capture; the models themselves are our own work and are not published. **Walkability** is a 0-10 score for how much of daily life sits within a walk of the average home. It weighs access to everyday destinations — groceries, food and drink, public transport, schools, parks, health, culture and services — along the real pedestrian network rather than a straight-line radius, so the things people use most often count for most. Amenities come from OpenStreetMap, schools from ACARA, stops and their service frequency from the state GTFS feeds, and walking is routed on an elevation-aware network, so hills genuinely shorten what is in reach. Every home in an area (a G-NAF address) is scored and the area takes the average — which keeps big rural areas honest: the town scores what the town deserves and empty paddocks do not vote. **Travel times and transit reach.** Walking time to the nearest stop and driving time to the capital are routed over the OpenStreetMap network; people reachable by public transport, and transit time to the city, combine that network with the GTFS timetables for a weekday morning. Drive times are free-flow, with no live traffic. **Reading them.** Derived scores compare within a level — suburb with suburb, council with council — and that is how the site frames them. Where the underlying map data is too thin to trust, mostly in regional and remote areas, the score is withheld (shown as no data) rather than published as a false near-zero. Walking times make no allowance for footpath quality, crossings, shade or perceived safety. **Attribution.** These measures are built on OpenStreetMap (ODbL, on-screen context only), routed with the open-source Valhalla and R5 engines; public transport stops and timetables from the state/territory GTFS feeds; schools from ACARA; home locations from Geoscape G-NAF; and elevation from the NASA SRTM digital elevation model (SRTM data courtesy of the U.S. Geological Survey). ## Known caveats - **Confidentiality perturbation.** The ABS randomly adjusts small cells, so very small counts may not sum exactly to their totals. - **Non-response.** Not everyone answers every question; "not stated" responses mean shares are of those who answered. - **Small areas are noisier.** The smaller the area, the more a handful of people moves a percentage — read SA1/SA2 figures with that in mind, and prefer larger areas for headline comparisons. - **Crime isn't comparable across states.** Each police service uses its own offence definitions and counting rules, so a crime rate is only safely compared with other areas in the same state. ## Start exploring - [Browse topics](https://censusatlas.au/topics) - [About CensusAtlas](https://censusatlas.au/about) Source: Australian Bureau of Statistics, Census of Population and Housing (2011, 2016, 2021), CC BY 4.0. CensusAtlas is independent and not affiliated with the ABS.