Facebook really is losing teen users to Instagram and Snapchat (FB, SNAP, TWTR)

Snapchat hotdog

It's true: teenagers really do think Facebook is less cool than Instagram and Snapchat.

That's according to a study by eMarketer, which predicted that monthly teen use of Facebook in the US and UK would decline faster this year than last year.

Monthly users aged between 12 and 17 years old will fall 3.4% to 14.5 million people this year, an accelerated decline from the 1.2% fall in 2016. It's the second year of teen use decline for Facebook, according to eMarketer.

The picture is similar in the UK. eMarketer doesn't give figures or state what its previous estimates were, but again reports percentage declines for teen and young users. Monthly users aged between 12 and 17 years old will go down by 2.8%, while those aged between 18 and 24 will go down 3.1%.

While a slowdown among a coveted, hard-to-please teen userbase is bad news, the flipside for Facebook is that they're turning to Instagram, which Facebook owns.

They're also turning to Snapchat. eMarketer even predicted that Snapchat would overtake both Instagram and Facebook in terms of teen users by the end of 2017 — a first.

"We see teens and tweens migrating to Snapchat and Instagram," said eMarketer analyst Oscar Orozco. "Both platforms have found success with this demographic since they are more aligned with how they communicate — that is, using visual content.

"Outside of those who have already left, teens and tweens remaining on Facebook seem to be less engaged — logging in less frequently and spending less time on the platform."

eMarketer predicted Snapchat's US userbase would grow 25.8%, and its UK base by 20.2% in 2017.

Instagram, it said, would grow 23.8% in the US and 34.8% in the UK.

This still leaves Facebook as the biggest social network, both in the US and the UK. It has 2 billion monthly users and took in a hefty quarterly profit. eMarketer social chart

But it should still be worried about Snapchat's popularity.

"Facebook is still the big winner in social media," said Bill Fisher, eMarketer’s UK senior analyst. "But it will be slightly concerned that younger people in the UK are having their heads turned by Snapchat. Of course, Facebook’s ownership of Instagram is softening the blow, and it will be further enthused to see Instagram’s longer-term prospects looking even better than Snapchat's."

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