I was recently working with a GPS device that returned coordinates in milliarcseconds (mas). Unfortunately, not all mapping applications (Google Maps, for example) can understand milliarcseconds. Therefore, I had to convert milliarcseconds to degrees.

The key to the conversion is understanding that one degree is equivalent to 60 arcminutes (arcmin or MOA). Therefore, one degree has 3,600 arcseconds (arcsec) or 3,600,000 mas.

So, to convert millarcseconds to degrees, simply divide by 3,600,000.