Wearables may be a niche product now, but all that’s about to change, predicts Cisco. According to Cisco’s Visual Networking Index report, there will be more than half a billion wearable devices in use every day by the time 2019 hits. Given the sheer number of wearables manufacturers at CES 2015, the upcoming launch of the Apple Watch, and the rumors swirling around more Android Wear devices, it seems entirely possible that the world is about to be flooded with wearables.

Of course, Cisco’s number doesn’t just include smartwatches — it also counts wearable cameras, fitness trackers, and so on. Still, considering that  wearables are a relatively new category, the idea that 578 million of them will be strapped onto people’s bodies in just four years time is rather impressive.

Related: Tablet sales slump for the first time ever

Cisco also estimates that the amount of data from wearables will increase by a factor of 18 during that time, though most of it will filter through users’ smartphones. In other words, you’re going to be seeing a lot more people tapping away at their wrists in the near future.

In addition to the huge wearable increase, Cisco expects to see smartphone ownership continue to rise to 5.2 billion by 2019. That’s almost exactly 1 billion more smartphone users than the world currently has (the figure stands at 4.3 billion). Naturally, as more people use the Internet on smartphones and wearables, data usage is also expected to rise dramatically. People used around just 30 exabytes of data in 2014, but that’s set to increase exponentially to 292 exabytes before 2020 arrives.