Interconverting lat/lon and UTM

This page is about converting locations between the latitude-longitude and UTM systems. Lat/lon format conversions are explained on the lat/lon page, UTM format conversions on the UTM grid page, and datum to datum conversions on the datums page.

If you use a GPS and have your locations stored as waypoints in lat/lon, you can convert those waypoints to UTM and vice-versa by changing the format setting of your GPS unit, as explained on the GPS page. Note that the datum will have to be changed separately (if needed). If you use WGS84 for lat/lon, the corresponding UTM grid reference will be WGS84, not GDA94. Also be aware of error and uncertainty when you convert this way.

Google Earth also offers this kind of 'settings' interconversion. The default system is lat/lon, and you can add a placemark by specifying its latitude and longitude. In the Google Earth 'Tools' menu, choose 'Options' and you can change 'Show Lat/Long' to Universal Transverse Mercator (UTM). Next, right-click on your placemark and choose 'Properties'. The placemark now has its location specified as Grid Zone, easting and northing. The datum will be the Google Earth default, WGS84, and the accuracy will be totally unbelievable (to the nearest 1 cm); see the error page.

Another one-at-a-time conversion is offered by LISTmap. You can enter a lat/lon in the search bar to go to a particular location, then use LISTmap's 'Locate Me Tool' to get the location's UTM grid references. Note that LISTmap assumes that the lat/lon is based on the GDA94 datum, and that you won't get a result if you enter a UTM grid reference in the search bar.

There are also two one-at-a-time Commonwealth Government online services. Go to the 'Geodetic Calculations - Redfearn's Formulae, Geographic to Grid' page to convert geographic coordinates (lat/lon) to a UTM grid reference in 6-digit easting, 7-digit northing format. Use that UTM format on the 'Geodetic Calculations - Redfearn's Formulae, Geographic to Grid' page to get lat/lon. In both cases pay attention to error.

For batch interconversions of a list of locations, I recommend two freeware tools, both of which are written for Microsoft Windows and downloadable as '.exe' files. Both also run very well on my Linux computer using the WINE compatibility layer; I'm not sure whether or how they can be used on OS X machines.

The two programs are LOTE 2.0 (2001) which is recommended by NASA, and the Australian GeoCalc 4.20 (1999). Both programs have excellent help files which explain how to do batch conversions.