Sales of phablets could reach as high as 120 million by 2018, according to research from analysis firm Juniper.
Devices with screens of 5.6-inches or more sold around 20 million units in 2013, Juniper calculates, with that number expected to jump year-on-year as more handsets flood the market.
Its believed the growth will be fuelled by users in Asian markets, especially China and South Korea. Google has been making headway with Android in these countries, while Apple has traditionally struggled to match the grip it holds in Europe and the US.
Juniper said its projected numbers could be even higher if an Apple phablet launches in the next few years. Cupertino is believed to be readying a 4.7-inch iPhone 6 for launch later this year, but will need to head closer to 6-inches in order to compete in this growing space.