Convert GDA94 to GDA2020

Convert coordinates from GDA94 (EPSG:4283) to GDA2020 (EPSG:7844) — official EPSG transformation parameters, accuracy and area of use, with a free in-browser converter.

From

Input (lon, lat (decimal degrees))

Output (lon, lat (decimal degrees))

Direct link to this transformation: epsgtransform.com/transform/epsg-4283-to-epsg-7844

About converting GDA94 to GDA2020

Converting from GDA94 (EPSG:4283) to GDA2020 (EPSG:7844) is the official transformation needed to migrate Australian spatial data from the 1994-era datum to the current 2020 realisation. The Australian plate has drifted ~1.8 m north-east since 1994, so GDA94 coordinates differ from modern GPS-derived positions by roughly that amount.

The published transformation is EPSG:8048 — a 14-parameter time-dependent Helmert transformation with millimetre-level accuracy. Geoscience Australia provides this as a standalone tool (GDA2020 Conformal+Distortion Transformation) for surveying-grade work; for general GIS use the simpler 7-parameter EPSG:8047 is accurate to a few centimetres.

Why people convert EPSG:4283 to EPSG:7844

Migrating pre-2020 Australian government data to current standard
Reconciling cadastral records with modern surveys
Federal mapping migration deadlines (target 2030)

Try it: Sydney Opera House

Input (EPSG:4283): 151.2153, -33.8568

Official EPSG transformations from GDA94 to GDA2020

The EPSG Geodetic Parameter Dataset defines 5 transformations between GDA94 (EPSG:4283) and GDA2020 (EPSG:7844). Each applies to a specific area — pick the one whose area of use covers your data.

GDA94 to GDA2020 (1)

EPSG:8048±0.01 mBest accuracy

Method:: Coordinate Frame rotation (geog2D domain)
Area of use:: Australia - GDA
Scope:: Transformation of GDA94 coordinates that have been derived through GNSS CORS.

Parameter	Value	Unit
X-axis translation(tx)	61.55	millimetre
Y-axis translation(ty)	-10.87	millimetre
Z-axis translation(tz)	-40.19	millimetre
X-axis rotation(rx)	-39.4924	milliarc-second
Y-axis rotation(ry)	-32.7221	milliarc-second
Z-axis rotation(rz)	-32.8979	milliarc-second
Scale difference(ds)	-9.994	parts per billion

Scale difference in ppb where 1/billion = 1E-9. See CT codes 8444-46 for NTv2 method giving equivalent results for Christmas Island, Cocos Islands and Australia respectively. See CT code 8447 for alternative including distortion model for Australia only.

GDA94 to GDA2020 (4)

EPSG:8444±0.05 m

Method:: NTv2
Area of use:: Christmas Island - onshore
Scope:: Geodesy.

Grid file: GDA94_GDA2020_conformal_christmas_island.gsb

See GDA94 to GDA2020 (1) (code 8048) for transformation using Helmert method which gives identical results.

GDA94 to GDA2020 (5)

EPSG:8445±0.05 m

Method:: NTv2
Area of use:: Cocos (Keeling) Islands - onshore
Scope:: Geodesy.

Grid file: GDA94_GDA2020_conformal_cocos_island.gsb

See GDA94 to GDA2020 (1) (code 8048) for transformation using Helmert method which gives identical results.

GDA94 to GDA2020 (3)

EPSG:8446±0.05 m

Method:: NTv2
Area of use:: Australia - onshore
Scope:: Transformation of GDA94 coordinates that have been derived through GNSS CORS.

Grid file: GDA94_GDA2020_conformal.gsb

Gives identical results to Helmert transformation GDA94 to GDA2020 (1) (code 8048). See GDA94 to GDA2020 (2) (code 8447) for alternative with local distortion modelling included. GDA2020 Technical Manual and fact sheet T1 give guidance on which to use.

GDA94 to GDA2020 (2)

EPSG:8447±0.05 m

Method:: NTv2
Area of use:: Australia - onshore
Scope:: Transformation of GDA94 coordinates when localised distortion needs to be taken into account, e.g. if GDA94 coordinates were derived from survey control monuments.

Grid file: GDA94_GDA2020_conformal_and_distortion.gsb

See GDA94 to GDA2020 (1) or (3) (codes 8048 and 8446) for alternative conformal-only transformation without local distortion modelling. GDA2020 Technical Manual and fact sheet T1 give guidance on which to use.

Convert EPSG:4283 to EPSG:7844 in code

The same transformation with common GIS tools and libraries:

from pyproj import Transformer

transformer = Transformer.from_crs("EPSG:4283", "EPSG:7844", always_xy=True)
x, y = transformer.transform(-73.9857, 40.7484)
print(x, y)

Source: EPSG:4283 — GDA94

geographic system using latitude and longitude on an ellipsoid · Area of use: Australia - GDA

+proj=longlat +ellps=GRS80 +no_defs +type=crs

More about EPSG:4283 →

Target: EPSG:7844 — GDA2020

geographic system using latitude and longitude on an ellipsoid · Area of use: Australia - GDA

+proj=longlat +ellps=GRS80 +no_defs +type=crs

More about EPSG:7844 →

Frequently asked questions

How accurate is the GDA94 to GDA2020 transformation?: The official 14-parameter EPSG:8048 is millimetre-accurate and includes a distortion grid. The 7-parameter EPSG:8047 used by browser tools is centimetre-accurate — fine for most uses, not for cadastre.
Why did Australia change datums?: GDA94 coordinates had drifted ~1.8 m relative to global GNSS positions due to plate motion. GDA2020 restores alignment with ITRF2014 at epoch 2020.0 and is accurate to GPS-derived coordinates as of that date.
How accurate is converting GDA94 to GDA2020?: The most accurate official EPSG transformation between these systems is accurate to about ±0.01 m within its stated area of use. Browser-based converters approximate datum shifts with Helmert parameters; for surveying-grade work apply the official transformation (including the grid-shift files listed below) in a desktop GIS.
Does my data leave the browser when I use this converter?: No. All coordinate transformations are computed locally in your browser using proj4js. The coordinates you enter are never transmitted to any server.

Need the reverse? Convert EPSG:7844 to EPSG:4283 →