Smartphone users comfortable with smaller screens could be in for a change by 2021, new figures show.

According to the International Data Corporation (IDC), phablets (phone tablets) with screens bigger than 5.5in will overtake traditional smartphones as the most popular mobile device. The data reveals that overall smartphone shipments will rise from 1.5 billion in 2017 to 1.7 billion in 2021.

Phablet shipments will grow from 611 million this year to 1 billion by 2021, which represents an annual growth rate of 18.1%. Traditional smartphones, however, will decrease by 7.4% per year. In 2012, phablets represented just 1% of the market.

According to IDC, video consumption, social media and gaming have all contributed to the primary force behind the switch. IDC mobile device tracker vie president Ryan Reith said phablets were approaching 50% of the market share. "The rapid transition to bezel-less smartphones will help minimise the device footprint while growing the screen size from previous generations," he said.

"Consumers continue to consume more video entertainment, gaming, social media and other data-heavy applications on their smartphones making the display size and type of critical factor in smartphone buying decisions."

Android and iOS continue to dominate the software battle for smartphones. The data from IDC shows both grew in the last financial year (iOS by 2.4% and Android by 1.7%). Combined other platforms, such as Windows, fell 78.8%.

Google's Android will still control the lion's share of the market (because different developers are free to use the platform) by 2021. In 2017, Android has 85.1% of the market compared to iOS's 14.8%. By 2021, Android will marginally increase its share to 85.3%. iOS will drop slightly to 14.6%.

Microsoft appears to have thrown in the towel on its Windows phones. In October, Microsoft vice president Joe Belfiore tweeted that building new features for the software was "not a focus".