Frequently Asked Questions: FAQ about GPS

Topic

15	How to convert between Swiss Grid and WGS84?

How to convert between Swiss Grid and WGS84?

Question:

How to convert between Swiss Grid and WGS84?

Answer:

• LAT/LON WGS-84 --> Swiss Grid CH-1903
  
  EWGS: Easting WGS-84 in degrees
  NWGS: Northing WGS-84 in degrees
  
  EA=(EWGS-7.43863)/57.29577951     easting from Berne in radiant
  NA=(NWGS-46.95108)/57.2957795    northing from Berne in radiant
  
  XCH= 600 + 1841.627*EA + 2520.1147*sin(EA) - 4654.4*EA*NA
  YCH= 200 + 6369.76*sin(NA) + 1591.87*EA*EA*(1-NA/.91) + 23.9*NA*NA
  
  These equations yield a precision of one to two meter for any point within Switzerland.

• Swiss Grid CH-1903 --> LAT/LON WGS-84
  
  XSG,YSG Swiss grid coordinates (based on km units)
  
  XB=XSG-600.000 coordinates relative to Berne
  YB=YSG-200.000
  
  N= 46.95108 + YB/111.18143955 - XB*XB/1332636
  E= 7.43863 + 57.29577951*arctan(XB/4360.68 + XB*YB/26378264)
  
  This conversion yields a precision of about 30 meter for points within Switzerland.