SAN MATEO, CA – Tablet shipments are expected to grow 58.7% year-over-year in 2013, reaching 229.3 million units, says International Data Corp.

IDC now predicts tablet shipments will exceed those of portable PCs this year, as the slumping PC market is expected to see negative growth for the second consecutive year. In addition, IDC expects tablet shipments to outpace the entire PC market (portables and desktops combined) by 2015.

While Apple has been at the forefront of the tablet revolution, the current market expansion has been increasingly fueled by low-cost Android devices, the firm says. In 2013, the worldwide average selling price for tablets is expected to decline 10.8% to $381. In comparison, the ASP of a PC in 2013 is nearly double that at $635. IDC expects tablet prices to decline further, which will allow vendors to deliver a viable computing experience into the hands of more people at price points the PC industry has strived to meet for years.

Another major shift in the tablet market has occurred around screen sizes. Apple's first generation iPad, which included a 9.7" display, was perceived by many as the sweet spot for tablets. That is, until 7" Android-based tablets began to gain traction in the market. Apple responded with the iPad mini in the fourth quarter of 2012, and in the space of two quarters, the sub-8" category exploded to overtake the larger-sized segment in terms of total shipments, says IDC.