The Population of Atlantis has been estimated by a number of Atlantologists, based on the data provided by Plato.

Otto Muck[098] considered the population of Atlantis to have been at least 20 million.
“Let us begin with the allegedly excessive numbers of inhabitants. This can be roughly calculated from the details Plato gives of the organisation of the Atlantean armed forces: 480,000 foot soldiers, 120,000 horsemen, 160,000 manning the 10,000 heavy chariots and 60,000 light chariots, and 240,000 sailors. These add up to approximately one million men under arms.” From this, Muck as extrapolated a total population of between twenty and forty millions.

Wolter Smit estimates(a) the population figure to be between 28 and 155 millions. Constantin Benetatos suggest(b) a lower figure of between 6 and 10 millions but also considers Plato’s data to be exaggerated.

When we consider that the entire population of the world in 10,000 BC has been calculated at 5,000,000(c). The same sources estimate the world population in the middle of the second millennium BC at around 35 million. Therefore, once again we are forced to view Plato’s numbers with some suspicion.

(a) http://was-this-atlantis.info/size.html
(b) http://www.atlantishistory.net/page8.htm
(c) http://www.census.gov/ipc/www/worldhis.html