SAN FRANCISCO, March 12 (Reuters) - Shipments of Apple Inc's iPads will fall behind the growing variety of tablets running Google Inc's Android platform for the first time this year as smaller-sized devices catch on with more consumers, research firm International Data Corp (IDC) said on Tuesday.
iPad shipments are expected to account for 46 percent of the market in 2013, down from 51 percent last year, IDC said. Devices running Android are expected to grow their market share to 49 percent this year from 42 percent last year.
IDC also raised its 2013 tablet shipment forecast to 190.9 million units, up from its previous forecast of 172.4 million units. Last year, global tablet shipments grew to 128.3 million units, up from 72 million in 2011, according to IDC.
Google's Nexus 7 tablet and Amazon.com Inc's Kindle, which uses its own customization of Android, made major inroads with consumers last year. In November, Apple launched its own foray into smaller-sized tablets with the iPad mini.
"One in every two tablets shipped this quarter was below 8 inches in screen size. And in terms of shipments, we expect smaller tablets to continue growing in 2013 and beyond," IDC said in a press release.
Last month, Hewlett-Packard Co announced the launch of the Slate 7 tablet powered by Android, a centerpiece of that company's effort to expand in mobile devices and reduce its dependence on the shrinking personal computer market.
IDC said tablets running Microsoft's Windows 8 platform would grow their market share from 1 percent last year to 7.4 percent in 2017.
Tablets running the Windows RT operating system, which is not compatible with older software that runs on Windows, will see their market share stay below 3 percent through 2017, IDC said.
"Consumers aren't buying Windows RT's value proposition, and long term we think Microsoft and its partners would be better served by focusing their attention on improving Windows 8," IDC said.