Tablet computers will outsell personal computers by 2015 globally in another sign of the shifting tech landscape, a survey showed Monday.

A report by the research firm Gartner said that the shift comes despite a cooling of the tablet market in 2014 and some stability in PC sales, due to upgrades of aging devices.

The research firm said it expects total PC sales this year of 308 million units, with some growth in "ultramobiles" offsetting declines in traditional desktop and laptop purchases.

For 2014, PC sales will still hold a lead over tablets -- with sales expected of 256 million units. But by 2015, tablet sales will hit 320 million to 316 million for PCs, it sales.

The prediction came in a report which said total device sales including PCs, tablets and mobile phones hit 2.4 billion units this year.

Gartner analysts said the tablet market is cooling a bit, with growth slowing to 23.9 percent this year, around half the pace of 2013. The PC market meanwhile is seeing relative stability -- with a decline expected of 2.9 percent after a 9.5 percent drop last year.

Gartner analyst Ranjit Atwal said PC sales are being helped by upgrades and replacements of aging devices.

"This year, we anticipate nearly 60 million professional PC replacements in mature markets," he said.

Sales of mobile phones are expected to reach 1.9 billion units in 2014, a 3.1 percent increase -- with smartphones accounting for two-thirds of the total.

Taking into account all the devices, Google Android is expected to represent around half of all sales -- 1.16 billion, Gartner said. Windows devices will account for 333 million while Apple's iOS and MacOS will total 271 million, the report said. rl/jm