Asked in Google Earth
How accurate is the Google Earth Ruler?
March 11, 2011 3:25PM
Pretty darn accurate. Try measuring something for yourself that you know the length of--it can get it almost exactly.
The Google Earth ruler is not accurate over long distances (e.g. > 5,000 km)
The official stance from Google is that it "makes no claims as to the accuracy of the coordinates in Google Earth. These are provided for entertainment only and should not be used for any navigational or other purpose requiring any accuracy whatsoever".