EMarketer claims 20m people in the UK will use a tablet this year, and while Apple’s device accounts for 59% of them, its share is expected to fall.

The company predicts that the number of people in the UK using tablets will grow from 20m to 34.8m people by 2017, half the population, by which point it expects tablets to be a truly "mass-market device" thanks to more affordable models like Amazon’s Kindle Fire and Tesco’s recently-launched Hudl.

Those devices are also expected to drive a surge in UK tablet market share for Google’s Android software. Of the 20m Brits using tablets in 2013, eMarketer expects 59% to be using iPads.

However, it claims that the growth rate for Apple’s device will be "a little over half that of tablets overall" in the face of growing competition from Android and Windows tablets.

eMarketer’s predictions are based on people who use a tablet at least once a month, whether they own it or are sharing the device with someone else in their household. The march towards mainstream acceptance is shown by the company’s claim that the fastest growth this year will come from under-12s and over-65s.

The stats suggest that 8.8% of British tablet users this year are aged 0-11, and a further 7.2% are aged 12-17. That indicates 3.2m children and teenagers using tablets in the UK. Tablet makers are responding to this growth already: the Hudl is being pitched as a family-friendly device, while Apple recently launched a dedicated Kids category in its App Store.

The growth of tablets has been rapid since late 2012, beating even the most bullish predictions for their popularity. In September 2012, for example, research firm YouGov claimed that there were 5.87m tablets in UK households, and that this would increase to just over 10m by August 2013.

YouGov was providing estimates for devices rather than users, which is one reason why eMarketer’s predictions now are so much higher.

Research firm IDC has predicted that more tablets will ship than desktop and laptop PCs combined in the final quarter of this year, taking tablets to shipments of 227.3m for 2013 as a whole.

Rival ABI Research backs up eMarketer’s predictions of strong growth for Android tablets too, claiming that Android tablet shipments overtook iPad for the first time in the second quarter of this year.