Gartner has revealed the level to which the wearables market is driven by the uptake of Bluetooth headphones and headsets.
According to the firm's calculations and predictions, Bluetooth audio will make up 150 million units shipped worldwide in the wearables category, out of a total of 310 million. By 2021, Gartner is predicting the wearables market will top 504 million units, with Bluetooth audio making up 206 million of the total -- at which time, the firm said it expects nearly all premium mobile handsets to lack a headphone jack.
The most profitable sector within wearables will continue to be the smartwatch category, with total global revenue in 2021 said to be $17.4 billion.
"The overall ASP [average selling price] of the smartwatch category will drop from $223.25 in 2017 to $214.99 in 2021 as higher volumes lead to slight reductions in manufacturing and component costs, but strong brands such as Apple and Fossil will keep pricing consistent with price bands of traditional watches," Gartner research director Angela McIntyre said.
Gartner said it expects Apple's share of the smartwatch market to fall from one third of the market in 2016 to a quarter in 2021, while it expects the market for children's smartwatches to make up 30 percent of shipments in 2021.
"These devices are targeted at children in the two to 13-year-old range, before parents provide them with a smartphone," the firm said.
Over the four years from 2017 to 2021, Gartner predicts overall smartwatch sales will almost double from 41.5 million units to 81 million.
The firm said it expects head-mounted displays to remain a niche device for gamers and to appear in certain repair and maintenance roles within businesses.
In research from earlier this month, Strategy Analytics said Xiaomi has dethroned Fitbit and Apple as the world's largest wearable vendor.
"Xiaomi's Mi Band fitness trackers are wildly popular in China, due to their highly competitive pricing and rich features such as heart-rate monitors, step-counters, and calendar alerts," Neil Mawston, executive director at Strategy Analytics, said in a statement.
Fitbit slid from 28.5 percent market share to 15.7 percent over the year, with shipments dropping from 5.7 million in Q2 2016 to 3.4 million last quarter.
"Fitbit is at risk of being trapped in a pincer movement between the low-end fitness bands sold by Xiaomi and the fitness-led, high-end smartwatches sold by Apple," Mawston said.
Gartner predicted the wearable category to grow from 44 million units this year, to 64 million in 2021.
In June, IDC said 125 million wearable devices will be shipped in 2017, with its definition of wearable not including Bluetooth audio devices.