This week, Mark Zuckerberg dropped the tidbit that Instagram has more than 200 million users, double the user base it had when Facebook acquired the photo-sharing service two years ago.
With 241 monthly active users worldwide, Twitter still enjoys a modest lead. But in the U.S., on smartphones -- the medium through which both services were built to be experienced -- Instagram seems to be pulling ahead.
In a new analysis, eMarketer estimates that 30.8 million Americans used Twitter on their smartphones in 2013. This year, that number will rise to 37.3 million. Instagram, meanwhile, had 34.6 million users last year and will reach 40.5 million in 2014.
The comparison is not quite exact. EMarketer notes that Instagram usage "all but exclusively takes place on smartphones," but the fact that some tiny proportion of 'grammers access the service through the web or on tablets means there's a possibility that Twitter could still have a tiny edge on phones.
But let's be real here. Instagram is ahead.
That said, Instagram penetration among smartphone users is slowing, and this year the rate of increase will fall to 17%, down from 23.9% last year. While the service will continue to grow, especially among men, who now make up only about one-third of its users, by 2018 it will only have about 56 million users, less than half the number of Americans who now use Facebook's phone apps.
