How do I add a custom projection to MapInfo and Discover


I've added a custom projection line to my MAPINFOW.PRJ but it does not appear in the select projection dialog box's list.


If the projection is not appearing in MapInfo Pro, it will need to added to the default MAPINFOW.PRJ file located in -

C:\Program Files\MapInfo\Professional (64-bit)

C:\Program Files (x86)\MapInfo\Professional (32-bit)

Note that these are read only locations, so you will need to copy the file to your desktop, edit it, and then copy back to overwrite with the changes.

If it is still not listed check the format is exactly correct by copying the exact formatting -

"--- Custom name ---"
"Projection name", x, x, x

You should also use DISCOVER>Projection Editor to create the custom coordinate system string.

If using Discover 2017 Update version or later, you only need to update the 1 PRJ file. Other PRJ files are kept in sync. Also there is a new Projection Editor tool to add custom projections, and update both files.

If you wish to share the same PRJ file on a network drive for all users, this can be set using the MapInfo Workgroup directory setting in PRO>Options>Directories.

On older versions,  Discover's reprojection tools and Discover3D use a separate projection file (to MapInfo Pro) which you will need to copy and paste the custom projection lines into It has the identical format as the Mapinfow.prj file..
It is located at-



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Last Updated on: 27th of August, 2019