The Longitude row was converted to positive/negative values (-180 to 180 degrees) from data in the format 0-360 degrees using the Excel formula: =if(A1>,180.0, A1-360, A1) . First we save the Excel Worksheet in the Excel 1997-2003 .xls format to ensure compatibility. Then we can open this file in ArcMap using the ‘Add Data’ button (a black cross on a yellow background . Alternatively you can select ‘Add Data’ from the Right click on the Table that you have just imported and select ‘Display X,Y Data’. This will allow us to convert the Table into point data. Make sure your ‘Y Field’ corresponds to you Latitude/Northing column and your ‘X Field’ to your Easting or Longitude column. If there is a message stating ” Unknown Coordinate System” click ‘Edit’ and then ‘Select a predefined coordinate system’. Choose the correct system for your data. In my case it is: Your data should now have appeared in the Layers List/Table of Contents and in the Data Frame. These data are not yet saved: they are temporary. Right click the Layer that you have just displayed (using step 2). Select Data>, and then Export Data to save the file as a Shapefile or similar. Source.