FRAMINGHAM, MA – A record-setting quarter for Apple's iPad led to a better-than-anticipated second quarter for the tablet market, according to preliminary data from research firm International Data Corp.

Total worldwide tablet shipments for the second quarter are estimated at 25 million units, up from 18.7 in the first quarter. That represents a quarter-over-quarter increase of 33.6% and a robust year-over-year growth rate of 66.2%, up from 15 million units a year ago.

IDC will release final shipment totals for the quarter later this month.

"Apple built upon its strong March iPad launch and ended the quarter with its best-ever shipment total for the iPad, outrunning even the impressive shipment record it set in the fourth quarter of last year," said Tom Mainelli, research director, Mobile Connected Devices. "The vast majority of consumers continue to favor the iPad over competitors, and Apple is seeing increasingly strong interest in the device from vertical markets—especially education. While iPad shipment totals are beginning to slow a bit in mature markets where the device saw early traction, growth in other regions is clearly more than making up the difference."

Apple shipped 17 million iPads during the quarter, up from 11.8 million units in 1Q12 and well above its previous record of 15.4 million in 4Q11. Apple wasn't the only company to experience solid growth in the second quarter. Four of the top five worldwide vendors saw their shipments increase year over year. Samsung experienced exceptional growth, and landed in second place with 2.4 million units shipped, up from 1.1 million units a year ago. Amazon rebounded from a sluggish first quarter to post shipments of 1.2 million units (the company, which ships its Fire tablet only in the US, entered the market in the fourth quarter). Asus shipped 855,454 units, well above its total of 397,048 units a year ago. Only fifth-placed Acer saw its year-over-year numbers decline, as it shipped 385,458 units this quarter, down from 629,222 units a year ago. It's worth noting that shipments of the well-received Google/Asus co-branded Nexus 7 aren't reflected in these totals, as that product officially began shipping into the channel in the third quarter of 2012.

IDC expects competition in the tablet space to continue to heat up in the second half of 2012. "In addition to major new products from Amazon and quite likely Apple, we can also expect an influx of Microsoft Windows 8 and Windows RT-based tablets starting in late October," said Bob O'Donnell, program vice president, Clients and Displays. "If anything, there's a real risk that people will have too many options from which to choose this holiday season. Consumers baffled by the differences between Amazon and Google versions of Android, or Windows 8 and Windows RT, may well default to market leader Apple. Or they may simply choose to remain on the sideline for another cycle."

Top 5 Vendors, Worldwide Media Tablet Shipments, Second Quarter 2012 (Preliminary) (in thousands)

Source: IDC Worldwide Quarterly Media Tablet Tracker, August 2, 2012.

Table Notes:

• Shipments include shipments to distribution channels or end users. OEM sales are counted under the vendor/brand under which they are sold.
• Data for all vendors are reported for calendar periods