Følg linket til en kørende version af world calculator ...
Follow the link to get to a working calculator ;-)
Enter the coordinates of opposing corners of the image. Geographic coordinates should be positive with N/S and E/W chosen for direction from the equator and the prime meridian. For UTM enter either positive or negative numbers for northing and easting, and leave the selectors on N and W. The results can be copied and pasted into your world file. Rotations are not handled in this implementation, so the second and third values will always be zero.
Read more: http://egb13.net/2009/03/worldfile-calculator/