The Geocentric Datum of Australia 2020 (GDA2020) and the Map Grid of Australia 2020 (MGA2020) are now the official datum and map projection for Australia. GDA2020 is a conventional static datum based on ITRF2014 at the reference epoch of 1 January 2020. Surveyor-General Victoria (SGV) has led the implementation of GDA2020 in Victoria and is actively encouraging and supporting organisations in the transition of their spatial data and applications to the new national datum.

Information to assist with transition to GDA2020 is available in the GDA2020 Factsheet (DOCX, 2.2 MB).


The Geocentric Datum of Australia 1994 (GDA94) and Map Grid of Australia 1994 (MGA94) is still maintained in Victoria. GDA94 is a static coordinate datum based on the International Terrestrial Reference Frame 1992 (ITRF92), held at the reference epoch of 1 January 1994.

The coordinates of features on maps based on GDA94 are no longer aligned with Global Navigation Satellite System (GNSS), such as GPS. Therefore, users are encouraged to transition to GDA2020. Differences of this magnitude become significant when it comes to applications that rely on accurate satellite positioning such as intelligent transport, precision agriculture and surveying.

GDA support

Further technical information, manuals, software and tools on supporting GDA2020 and GDA94 are available in the ICSM website.

Survey Control Network

The accurate realisation of GDA2020 and GDA94 is maintained in Victoria through the repeated adjustment of the Victorian survey control mark network of survey observations. This data set is regularly updated with new observations and readjusted to derive new estimates of survey mark coordinates. These refinements to the network enable the derivation of GDA2020 and GDA94 coordinates on new survey marks and improved coordinates on existing marks.

AMGVG conversion software

Download and then execute the program to perform calculations with coordinates. Note this software does not transform coordinate information between AGD and GDA, either geographical or UTM grid coordinates.

To change between AMG and MGA input screens, enter either A or M respectively at Select Option.

When in the MGA mode calculations for Vicgrid are performed relating to Vicgrid94 specifications.

AMGVG.exe Version 3.2 June 2010 (ZIP, 58.1 KB)

Scale factor calculations

A spreadsheet to assist with computing Point Scale Factor, Height Factor and Grid Convergence calculations is available for download.

Scale/Height Factor Calculations and Grid Convergance (Excel, 190.0 KB)

Page last updated: 09/06/20