Convert Coordinates

Last updated 14 July 2007

This program allows you to easily convert AGD66 map coordinates to GDA94 and vice-versa. It also supports AGD84. All formulas used are from the Geodetic Datum of Australia Technical Manual.

Download ConvertCoords (vers 1.4) here. (114 k Zipped Windows exe)

How to use the program

When you run ConvertCoords, you are presented with a dialog consisting of three areas. The box at the top allows you to select the datum of your input coordinates (e.g. AGD66) and the datum of the desired output coordinates (e.g. GDA94). It also allows you to enter the zone for the map you are working with (e.g. 56). The zone is usually shown in the legend area of the map.

The input coordinates box has three radio buttons at the top which allow you to select easting and northing, lat/long in deg/min/sec, or lat/lon in decimal degrees as the input mode. When you enter eastings and northings, remember to include all the digits (e.g 345700). Sometimes the leading digits of the easting and northing are not shown on topo maps, or are shown with small numbers. When entering lat/longs, enter the degrees, minutes, and seconds in the separate input fields provided. See my grid references and datums page for more info.

When you press the "Convert" button, the output coordinates box will contain the converted values. The formulas used are accurate to about 1 metre.

Other coordinate systems

If you want to convert from old 1:250,000 miles maps into metric AGD66 or GDA94 coordinates, I have created a program which does this in the Gosford/Wyong region with an accuracy of about +/- 250m. You can download this here. You enter coordinates in yards, e.g. 420000 yE, 860000 yN and you get back coordinates in metres in either the AGD66 or GDA94 datums. There is a partial scan of the Sydney 1:250,000 map here so you can see how these coordinates work. The simple algorithm used is here.

If you're interested in New Zealand datum conversions, I've put some information about this here.

Feedback is welcome.

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