Microsoft today announced that Windows 10 is now installed on over 400 million devices. It took the latest and greatest operating system from the company about 14 months to hit the new milestone.

Windows 10 was installed on over 75 million PCs in its first four weeks. It passed 110 million devices after 10 weeks, 200 million in under six months, 270 million after eight months, 300 million after nine months, and then 350 million after 11 months. Microsoft was aiming for 1 billion devices running Windows 10 “in two to three years,” but recently the company backpedaled on that goal.

Here’s the progress in a chart, with Windows 8 thrown in for context (Microsoft stopped reporting Windows 8 milestones after 200 million):

windows_10_400_million

As you can see, Windows 7 and Windows 8 milestones were similar for the first six months or so, though it quickly became clear that Windows 8 was not selling as quickly as its predecessor did. Windows 10 has been ahead of both from the start, and while the slope of its growth has become less steep, it’s still very strong. Windows 10 got to 400 million devices about 7 months sooner than Windows 7.

Windows 10 adoption is faster than its predecessors for a number of reasons. Here are the three big ones:

  • Windows 10 was available as a free upgrade for Windows 7 and Windows 8.1 users during its first year. This is why Microsoft counts “active devices” with Windows 10 rather than “license sales.”
  • Microsoft is also counting phones running Windows 10 Mobile (both purchased and those that have upgraded) in the total figure. Xbox Ones, Surface Hubs, and HoloLens devices are also included.
  • And finally, like with all Windows releases, there are more Windows computers now than there were before, not to mention more people in the world. The pie has grown, so the potential number of devices that can be running Windows 10 is larger than it was years ago when previous Windows versions were released.

Windows 10 is a service, meaning it was built in a very different way than its predecessors so it can be regularly updated with not just fixes but new features too. The most recent significant update is the Windows 10 Anniversary Update, released last month.