UTM has nothing to do with EPSG 3785 and Google maps.

If your desired point of the earth has negative lat/lon in degrees, the Google mercator coordinates are negative as well.

If you have UTM coordinates, they are always positive, but you need the UTM zone they are laying in. For the southern hemisphere, positive y counts from the south pole, for the northern hemisphere from the equator.

You can find formulas for UTM here: http://en.wikipedia.org/wiki/Universal_Transverse_Mercator_coordinate_system

Your zone might be UTM 30S.

UTM has nothing to do with EPSG 3785 and Google maps, apart from the WGS84 ellipsoid and datum. And WGS84 in degrees is yet another coordinate system.

If your desired point of the earth has negative lat/lon in degrees, the Google mercator coordinates are negative as well.

If you have UTM coordinates, they are always positive, but you need the UTM zone they are laying in. For the southern hemisphere, positive y counts from the south pole, for the northern hemisphere from the equator.

You can find formulas for UTM here: http://en.wikipedia.org/wiki/Universal_Transverse_Mercator_coordinate_system

Your zone might be UTM 30S.

UTM has nothing to do with EPSG 3785 and Google maps.

If your desired point of the earth has negative lat/lon in degrees, the Google mercator coordinates are negative as well.

If you have UTM coordinates, they are always positive, but you need the UTM zone they are laying in. For the southern hemisphere, positive y counts from the south pole, for the nortehren hemisphere from the equator.

You can find formulas for UTM here: http://en.wikipedia.org/wiki/Universal_Transverse_Mercator_coordinate_system

Your zone might be UTM 30S.

UTM has nothing to do with EPSG 3785 and Google maps.

If your desired point of the earth has negative lat/lon in degrees, the Google mercator coordinates are negative as well.

If you have UTM coordinates, they are always positive, but you need the UTM zone they are laying in. For the southern hemisphere, positive y counts from the south pole, for the northern hemisphere from the equator.

You can find formulas for UTM here: http://en.wikipedia.org/wiki/Universal_Transverse_Mercator_coordinate_system

Your zone might be UTM 30S.