By the Numbers: Google+ the Biggest Social Network Launch Ever?

Two-week-old Google+ has 10 million users, Google CEO Larry Page announced yesterday. That’s an enormous number, and makes it likely that Google+ has had the fastest out-of-the-gate velocity of any social network ever.

Of course, Google itself has one billion monthly unique visitors and just a teensy bit of brand recognition, and it seeded its new network carefully. But Plus is invite-only. Just imagine what would happen if Google opened the floodgates by promoting Plus on all its products.

If we look back, Google actually did have a bigger social network launch in the past, but not organically: It rolled out Buzz as a feature of Gmail available to all users. (Google doesn’t say how many Gmail users there are, but it’s well into the millions.)

Facebook, by contrast, took more than two years to reach 10 million users, and only hit the milestone after opening its network beyond college and high-school students.

Facebook’s numbers are slightly different, because it only counts users who were active within the last month. But at this point, every single Google+ member has been active within the last month.

I’d like to cast a broader net for examples, if anyone has them, but I’m having trouble finding historical active user counts for fast-growing networks like Sina Weibo. We also know Twitter grew somewhat slowly out of the gate, but it has resisted disclosing official active user counts.

Products built on top of existing social networks, and ones built for virality rather than invite-only rollout, however, have the potential for a much faster growth curve. Zynga’s most recent launch, Empires & Allies, got to 10 million users in nine days, just slightly behind the pace of CityVille, according to Inside Social Games and AppData.

UberMedia CEO Bill Gross, whose company is currently most active in the Twitter ecosystem but will presumably also develop clients for Google+, recently predicted that Google+ would hit 100 million users faster than any service in history. Well, Google’s numbers don’t make that a reality yet, but there’s only 90 million to go!

Meanwhile, Page also said on Thursday that Google+ facilitates one billion items shared and received per day. We clarified with Google the way it calculated this number.

Essentially, each counted “share” is the number of people who potentially see any one item.

If a user shares a picture with a Google Circle of 40 people, that counts as 40 shares — even if all 40 people don’t actually look at the photo. If a user shares something publicly, it’s not counted.

Google said this is consistent with the way it counts sharing in Gmail and other products. However, it’s a bit of a tricky metric; at first glance it would be easy to think that Google means one billion items are posted to Google+ on a daily basis already — which it doesn’t.

One interesting side note about Google+ reaching 10 million users — the milestone had actually been estimated by an outside researcher using fascinating methodology. Paul Allen, the founder of Ancestry.com who is now at FamilyLink, calculated the percent of the U.S. population that had signed up for Google+ by comparing user surnames to census data and extrapolating for international users. He estimated Google+ had 10 million users as of July 12 (two days before the second-quarter earnings announcement).

After earnings came out yesterday, Bradley Horowitz, the Google VP who coleads Plus development, gave credit to Allen in a Google+ post of his own. “BTW, +Paul Allen… Tip of the hat to you sir. Neat parlor trick. Statistics FTW!”

Photo credit: CAPE CANAVERAL, Fla. — NASA