In the election chat room I gave a count of the number of users allowed to vote: 126 users. I did this by looking at the users page and just counting them by hand. It started a series of others calculating the number and getting different answers. I am thrilled that it inspired others to take notice. Since we are getting different numbers and some are using what I would consider a more accurate means of counting (ref) the question is as the title.
How can the actual count of those eligible to vote be determined?
A related question if the number is different than what can be derived by counting the users page is why a difference in the two ways? E.g. Are there people allowed to vote that are not showing up on the users page? etc.