This year, 84.8 million people in the US—or roughly a quarter of the population—will use Snapchat, a 7.1% increase from 2017, according to eMarketer estimates.
By that metric, it will grow faster than Facebook and Twitter—which will see user counts rise just 0.9% this year—but slower than Instagram (up 13.1%).
"Monthly users are still growing even though Snapchat reported a decline in daily users in Q2," said eMarketer senior forecast analyst Chris Bendtsen. "Engagement among users may be down—in large part due to the unpopular redesign from earlier this year—but new users are still coming to the platform."
Snapchat is the No. 1 social network among teens. In fact, it will continue to add users ages 12 to 17, while Facebook lose users in that cohort.
What's more, for the first time, both Snapchat and Instagram will gain the same amount of new users (1.8 million) this year under the age of 25. "This highlights the competition Snapchat now faces among their biggest age demographic," Bendtsen said.
"One major challenge to Snapchat’s future growth will be Instagram, in particular its Stories feature. Instagram says 400 million people per day now use Stories. That’s more than double Snapchat’s worldwide daily active user base," wrote principal analyst Debra Aho Williamson in a recent eMarketer report, Snapchat and Twitter 2018.
Interestingly, the proliferation of Stories, one of Snapchat's key growth drivers, is being driven by adults ages 25 to 44—essentially those slightly older than the majority of Snapchat users.