Paul Allen, a Google+ watcher whose estimates about the social network’s growth have proved accurate in the past, claims that the site now has 62 million users and is adding 625,000 new users per day.

“It may be the holidays, the TV commercials, the Android 4 signups, celebrity and brand appeal, or positive word of mouth or a combination of all these factors,” Allen wrote on his G+ profile page Tuesday, “but there is no question that the number of new users signing up for Google+ each day has accelerated markedly in the past several weeks.”

Allen, the founder of Ancestry.com, takes an unusual approach to come by his estimates: He and his staff run hundreds of queries on surnames they’ve been tracking since July and then extrapolate the size of the network.

At this rate, Allen writes, G+ will reach 100 million users by Feb. 25, 2012 and 200 million by Aug. 3. By this time next year, G+ will have close to 300 million users.

Allen, however, doesn’t address how many of those 62 million are active users. Experian Hitwise, however, found that those users are on the rise as well, though they represent a fraction of G+’s base. Hitwise found that total visits to G+ hit 9.4 million for the week ending Dec. 17, the most recent full week it tracked. That was a nice jump over the 7.2 million visits G+ experienced in the comparable week in November, but below the 15 million visits to G+ for the week ending Sept. 24, when Google opened the previously invitation-only site to the public.

Google’s last official acknowledgement of G+’s membership came during a conference call with analysts, when CEO Larry Page pegged the figure at 40 million.

More About: Experian Hitwise, Google, Paul Allen

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