The computation of magnetic declination (difference between magnetic and geographic north), compass variation (difference between magnetic and grid north) and other quantities of the magnetic field (such as inclination or field strength) is possible with an online service offe by the geomagnetism group of the University of Neuchâtel.
As Input on this page you need the coordinates of a point in Swiss projection coordinates. If you only know the geographic coordinates, you have to convert them first with our service NAVREF.