How To: Define a custom projection for a geodatabase


This article describes how to define a custom projection for a geodatabase using ArcToolBox.


As an example, we use the Wisconsin Tranverse Mercator projection with the following parameters as the custom projection:

  • Map Projection: Transverse Mercator
  • Central Meridian: -90
  • Latitude of Origin: 0
  • Scale Factor: 0.9996
  • False Easting: 520,000
  • False Northing: -4,480,000
  • Units: Meter
  • Datum: NAD 1983
  1. Start ArcToolBox.
  2. Open the Data Management Tools > Projections toolbox.
  3. Double-click Define Projection Wizard (shapefiles, geodatabases).
  4. Click the Browse icon and navigate to the location of the geodatabase.
  5. Select the feature class and click the Add button.
  6. Click Next.
  7. Click Select Coordinate System.
  8. Click New in the Spatial Reference Properties dialog box.
  9. Select the projection in the popup window. Projected applies to the Wisconsin Transverse Mercator projection example.
  10. Type a name for the new projection.
  11. Set Name to Transverse_Mercator.
  12. Type the parameters for the projection. See the parameters for the Wisconsin Transverse Mercator projection listed above.
  13. Set the Linear Unit to Meter.
  14. Click the Select button to load the Geographic Coordinate System.
  15. Open the North America folder.
  16. Select North American Datum 1983.prj and click Add.
  17. Click OK.
  18. Click Apply and OK to close the Spatial Reference dialog.
  19. Click Next.
  20. Review the Summary and click Finish.