Best QGIS Projection for Australia: A Guide
When working with spatial data in Australia using QGIS, choosing the right projection is crucial for accurate mapping, measurement, and analysis. Projections transform the 3D shape of the earth into a 2D map, and different regions require different coordinate systems to minimize distortion.
Recommended Projection: GDA2020 / MGA Zone
The most widely used projection for Australia in QGIS is based on the Geocentric Datum of Australia 2020 (GDA2020), which is the latest official geodetic datum replacing GDA94. It aligns Australia’s spatial data more closely with global positioning systems (GPS).
Key Projection:
- Name: GDA2020 / MGA Zone XX (replace XX with the appropriate UTM zone)
- EPSG Code: 78XX (e.g., EPSG:7844 for MGA Zone 56)
- Projection Type: UTM (Universal Transverse Mercator)
Australia spans multiple UTM zones:
- Zone 49: Westernmost areas (e.g., Perth) – EPSG:7841
- Zone 50–56: Covers the rest of the country from west to east
- Zone 55: Includes Melbourne and Hobart – EPSG:7843
- Zone 56: Includes Sydney, Canberra, and Brisbane – EPSG:7844
When to Use GDA94
Some legacy datasets still use GDA94, so it’s important to know the equivalent EPSG codes for backward compatibility:
- GDA94 / MGA Zone 56: EPSG:28356
However, for new projects, GDA2020 is preferred due to better GPS alignment.
National Projection: Albers Equal Area
For national-scale datasets, where preserving area is more important than local accuracy, the Albers Equal Area projection is often used.
Key Projection:
- Name: GDA2020 / Australian Albers
- EPSG Code: 3577
- Use Case: National-scale maps, environmental data, census datasets
How to Set Projection in QGIS
- Open your project in QGIS.
- Go to Project > Properties > CRS.
- Search for the desired EPSG code (e.g., 7844 for MGA Zone 56).
- Select it and click OK.
You can also right-click layers to reproject them individually.
Summary
| Use Case | Projection | EPSG Code |
|---|---|---|
| Local mapping (e.g., Sydney) | GDA2020 / MGA Zone 56 | 7844 |
| Legacy mapping | GDA94 / MGA Zone 56 | 28356 |
| National-scale mapping | GDA2020 / Australian Albers | 3577 |
Final Tip
Always check the metadata of your spatial datasets to ensure consistent CRS use across all layers. Using the appropriate projection improves spatial accuracy and prevents alignment issues in your QGIS project.
