Thanks for your help
See GetDeviceCaps()
With the HORZRES and the HORZSIZE (or the Vert versions)
HORZSIZE = page width in mm.
HORZRES = page width in pixels.
mm = GetDeviceCaps( hPrinter,HORZSIZE);
pix = GetDeviceCaps( hPrinter,HORZRES);
pixpermm = pix / mm;
pixperinch = (pix * 254) / (mm*10);
You can also use SetMapMode to change the coordinate system.
Eelke