Google+ will pass 10 million members today, less than two weeks after launch, according to analysis of registered surnames on the social networking site.

Ancestry.com founder Paul Allen has been taking samples of surnames on Google+ and measuring them against the US Census.

Allen reckons that by the end of Tuesday, Google+ will have sailed past the 10 million members mark, which is a huge increase from his 4th July estimate of 1.7m.

20m by the weekend?

In a post on his Google+ profile, he says: "My latest estimate tonight shows approximately 9.5 million users. This suggests that 2.2 million people have joined Google+ in the past 32-34 hours.

"I project that Google will easily pass 10 million users tomorrow and could reach 20 million user by this coming weekend if they keep the Invite Button available."

Google has refused to be drawn on exactly how many people have signed up to use Google+, but Chairman and former CEO Eric Schmidt has admitted that there already millions of users.

We've noticed a marked increase in friends adding us to their circles in recent days, and while Allen's methods aren't, by his own admission, perfect, the methodology at least gives us a good indication of the speed at which Google+ is growing.

If Google keeps the invite process open then there really is no limit to how fast the uptake will be. Right now, it's only 740m users behind Facebook!

Link: Paul Allen on Google+