SAN MATEO, CA – IDC yesterday lowered its forecast for worldwide tablet shipments but said sales would still rise more than 53% year-over-year. According to the latest forecast from the market research firm, table shipments are expected to reach 221.3 million units in 2013, down slightly from a previous forecast of 227.4 million but still 53.5% above 2012 levels.

Shipment growth is forecast to slow to 22.2% year over year in 2014 to a total of 270.5 million units. By 2017, annual market growth will slow to single-digit percentages and shipments will peak at 386.3 million units, down from the previous forecast of 407 million units.

One key factor to watch going forward is the mix of small vs. large tablets. The market has trended toward small tablets in a big way over the last 24 months, but the rise of large phones could well push consumers back toward larger tablets as the difference between a 6" smartphone and a 7" tablet isn't great enough to warrant purchasing both. Apple's launch of the iPad Air, a much thinner and lighter version of its 9.7" product, could herald another market transition back toward larger screens, presuming consumers are willing to pay the higher costs associated with bigger screens.

"In some markets consumers are already making the choice to buy a large smartphone rather than buying a small tablet, and as a result we've lowered our long-term forecast," said Tom Mainelli, Research Director, Tablets. "Meanwhile, in mature markets like the US where tablets have been shipping in large volumes since 2010 and are already well established, we're less concerned about big phones cannibalizing shipments and more worried about market saturation."

A transition toward larger tablets could be a positive development for Windows tablets, which generally benefit from a larger screen area. Even so, Windows-based tablets are not expected to steal share from tablets running iOS and Android until the latter part of the forecast.

"For months, Microsoft and Intel have been promising more affordable Windows tablets and 2-in-1 devices," said Jitesh Ubrani, Research Analyst, Worldwide Tablet Tracker. "This holiday season, we expect a huge push for these devices as both companies flex their marketing muscles; however we still don't expect them to gain much traction. We're already halfway through the holiday quarter, and though there have been some relatively high-profile launches from the likes of Dell, HP, and Lenovo, we've yet to see widespread availability of these devices, making it difficult for Windows to gain share during this crucial period."

Tablet OS Market Share, 2012 - 2017

Source: IDC Worldwide Quarterly Tablet Tracker, December 2013

* Forecast