Facebook a month away from 700 million users?

When Facebook began, a million users was a big deal. Then it hit 100 million, then 500 million. Now, one billion doesn't seem so far off now that unofficial stats on Facebook point to the sprawling social network reaching 700 million active monthly users in as little as a month from now, maybe two.

Inside Facebook, an independent news and analysis site focused on Facebook, has revealed that "Facebook grew by 21.5 million new users in March to reach 661.5 million monthly active users worldwide," which puts it on track for an expectation of lucky 700 million by this summer.

In the U.S., Facebook's steady growth added 2.78 million users in March, for a total of about 155 million active monthly users. This aligns pretty much with comScore, which recorded about 153 million monthly actives, and an increase of about 15 million worldwide every month.

Inside Facebook acknowledges its numbers aren't in sync with other third-party stats trackers, such as "Google’s DoubleClick Ad Planner service shows Facebook with an extremely high 860 million monthly active users, fully 270 million above what we previously recorded. We’re not sure what accounted for the difference." On the other end of the spectrum, Inside Facebook's numbers diverge from Quantcast's lower showing of 136 million monthly Facebook users.

From Facebook itself, its publicly released stats remain at "more than 500 million," (from July) although it's been widely reported it crossed 600 million late last year by several outlets, including All Facebook and Business Insider