Windows 10 has already been installed on over 75 million PCs and tablets, according to Microsoft. Now, a new survey of Windows Store apps shows that Microsoft's latest OS is already taking a huge amount of market share away from Windows 8.1.

AdDuplex survey of Windows

AdDuplex, which runs an in-app ad service for both Windows Phone and Windows Store apps, looked at its data from 173 Windows 8.1 apps running a recent version of its SDK. It showed that when combining the numbers from Windows 10 and Windows 8.1 PC and tablet installs, Windows 10 was already being used by 39% of those devices, compared to 61% for Windows 8.1.

Windows RT

Those numbers also include PCs that run Windows RT, which doesn't have an upgrade path to Windows 10. AdDuplex looked at its data again and removed the Windows RT numbers, which showed Windows 10 with an even bigger 41.2% share compared to Windows 8.1 with 58.8%

AdDuplex does note that some of those Windows 10 installs could have been upgraded from Windows 7 PCs, or may have come pre-installed on a new PC or tablet. However, they still give a general trend that the adoption of Windows 10 has been quite strong, most likely due to Microsoft's free upgrade offer.

Source: AdDuplex