PC shipments are expected to fall by 3.8% to sales of over 300 million units in 2014, according to a report from the International Data Corporation (IDC).
Shipments are expected to decrease by 10.1% in 2013, more than the previous estimate of 9.7% for the year.
The report said windows devices will account for 10% of a combined PC and Windows Tablet market by 2016, representing an important growth segment for the PC ecosystem.
The decline is driven by a lack of interest in PCs along and fewer replacement of already installed systems.
IDC Worldwide Quarterly PC Trackers senior research analyst Jay Chou said:"While IDC research finds that the PC still remains the primary computing device - for example, PCs are used more hours per day than tablets or phones - PC usage is nonetheless declining each year as more devices become available."
"And despite industry efforts, PC usage has not moved significantly beyond consumption and productivity tasks to differentiate PCs from other devices. As a result, PC lifespans continue to increase, thereby limiting market growth."
Loren Loverde IDC Worldwide Quarterly PC Trackers vice president said: "The emergence of 2-in-1 devices designed to function in both clamshell and slate configurations - many of which will run Windows - along with Windows-based tablets themselves, is expected to provide some new volume for the Windows platform as well as the PC vendors and other parts of the traditional PC ecosystem in coming years."
According to the report, the Windows-based tablet market is expected to reach 39.3 million units in 2017 from 7.5 million in 2013.