The Google+ population reached 7.3 million on Sunday, and likely increased to 10 million yesterday, according to an analysis by Paul Allen, the founder of Ancestry.com and chief executive of Facebook app maker FamilyLink.com, ZDNet reported.
This estimate was done based on data about surname popularity from the U.S. Census Bureau.
“By using a sample of 100-200 surnames, I am able to accurately estimate the total percentage of the US population that has signed up for Google+. Then I use that number and a calculated ratio of US to non-US users to generate my worldwide estimates,” Allen wrote in a post on Google+, The Telegraph reported.
If Google keeps the Google+ invitation button active, Allen expected Google+ users to exceed 20 million by the weekend.
Google has not yet released official usage figures for its social networking service.
Facebook last week announced to reach 750 million users, and Twitter has more than 300 million users.