iCrossing came to this precise date by using linear regression to extrapolate Facebook growth data from the end of 2008 to the present. The end of 2008 was chosen as a starting point because that's when Facebook started to show the linear growth rate it has today. Between 2006 and mid-2008 Facebook was growing exponentially.
In a blog post, iCrossing writes that much of this growth will likely come from emerging Facebook markets, as the growth rates of early-adopters like the U.S. and U.K. have slowed or stopped. According to The Telegraph, Facebook usage in the UK fell by more than seven percentage points in 2011. The U.S., which according to data from Optim.al accounts for 19.7 percent of the Facebook population, has also seen a user slowdown. In October, the number of Americans who visited Facebook grew only 10 percent, which is down from 56 percent the previous year, reports The New York Times.
This slowdown is at least partially due to the fact that the social network is beginning to reach market saturation in some of its earlier markets. In saturated markets, a Facebook user increase will only occur as a result of population growth.
According to Optim.al, there are currently 155.7 million Facebook users in the United States. Other internet research companies put that number even higher. According to comScore data reported by TechCrunch, Facebook had 221 million unique visitors in November, which accounts for roughly 75 percent of the U.S. population.
Facebook has hardly reached market saturation in countries like India and Brazil. In India only 3 percent of the population uses Facebook, and that number is increasing rapidly. In the past nine months, Indian Facebook users have gone from 22 million to 36 million, reports iCrossing.
Facebook's user base far exceeds that of other social networks. At Facebook's F8 conference in September, the company revealed that it had passed 800 million users. In September, Twitter CEO Dick Costolo announced that the site had 100 million active users. According to unofficial G+ statistician Paul Allen, Google's social network may have exceeded 62 million members in December.