In 2019 as many as 245 million wearable devices will be sold, according to CCS Insight's latest wearable tech report, Wearables Forecast Worldwide, 2015 - 2019. For wearables, this number is huge. In 2015, the biggest sellers like Fitbit and Apple are selling around 4.4 million and 3.6 million devices a quarter respectively. And CCS predicts that by the end of this year, 84 million devices in total will have been sold in 2015.
So what will the world be wearing in four years? Activity and fitness trackers will make up 50% of sales. Smartwatches take second place but will make up over half of the actual revenue made from wearable tech sales - unsurprising as the likes of the Apple Watch are already selling for higher prices than say, a Fitbit Charge HR.
As a result of this growth, the wearables market as a whole will be worth $25 billion, up from just $9 billion in 2015.
"Those who labelled Apple Watch a failure need to think again," said Ben Wood, CCS Insight's chief of research. "In its first quarter of sales it accounted for around $1 billion of revenue and we expect sales to continue to rise, particularly in the all-important fourth quarter.
"As we predicted, consumer awareness of wearables in key markets like China, the US and UK has gone sky-high in 2015. We believe this can be attributed to what we are calling the 'Apple Watch effect' as well as the growing success of brands such as Fitbit in the US and Xiaomi in China."
China is a key country for the future of wearable tech. Of the 84 million units sold in 2015, CCS predicts that a huge 18.5 million of these will be fitness trackers sold in China by Xiaomi and new rivals in this space.
The third biggest category for the next three years is a bit of a surprise - wearable cameras including GoPros will continue to sell more and more, up to 19 million by 2017.
VR headsets and augmented reality smartglasses make up smaller portions of the overall sales, indicating that these two futuristic technologies will need five years or more to really hit the mainstream.