Mobile User Bases at Facebook and Twitter Keep Growing.

In the US, 28 million people will use Twitter on their mobile phones at least monthly this year, eMarketer estimates. That’s up 22% over 2012 figures but still a far cry from earlier growth levels. Twitter mobile users will account for just 11.4% of mobile phone users and 8.8% of the overall population.

This is eMarketer’s first time estimating Twitter usage on mobile phones. Though penetration of the overall population is low, usage among all mobile phone social network users is substantial, at a 28% penetration rate. That figure will actually fall in coming years, even as mobile phone Twitter usage grows in absolute numbers, due to the expected overall growth of mobile phone social networking, in particular on Facebook.

Smartphone users will also be more likely than average to use Twitter via mobile phone, with 18.5% of all smartphone users doing so this year. These users will account for 92.5% of all mobile phone Twitter users—and growth among smartphone users will be faster as well throughout the forecast period. By 2017, eMarketer expects one in five smartphone users to access Twitter at least monthly on their mobile phone.

The mobile Twitter population is not huge, but neither is the overall Twitter population in the US, estimated to reach 36.8 million users this year. That means 76% of all US Twitter users will access the service via mobile phone, rising to 87% by 2017.

Mobile Facebook usage will be significantly more widespread. This year, eMarketer estimates, just shy of 100 million Americans will access their Facebook account via mobile phone at least monthly. Nearly all mobile social network users will use Facebook via mobile. The overall mobile Facebook population will increase by more than 50% between this year and 2017, the end of eMarketer’s forecast period.

Despite these high mobile usage numbers, the overall size of Facebook’s US audience means the share who will access the social network on their phones is still smaller than that of Twitter—but not for long. eMarketer estimates 67.6% will do so this year, rising to 95.5% by 2017.

eMarketer bases its estimates of US Facebook and Twitter usage on the analysis of survey and traffic data from research firms and regulatory agencies, historical trends, company-specific data and demographic and socioeconomic factors.

For more information at