Redmond's newest operating system hit the 200 million milestone on January 4, and if you go back a little further to October 6 last year, that was when the company announced Windows 10 had reached the 110 million mark.
So from October to January, a period of three months, 90 million people adopted the OS, and from January to May, in other words four months, 100 million people have taken the plunge.
A quick bit of rough napkin maths reveals that the average pace of adoption has thus slowed a little, from around 30 million people per month at the tail end of 2015, to 25 million people per month this year.
However, there's every chance it will speed up again, as the end of July deadline for a free upgrade from Windows 7/8.1 looms. That will force the hand of those who have been sitting on the fence, or just plain haven't been bothered to deal with the hassle of making the move, as they need to click the upgrade button soon or potentially end up paying for the OS at a later date.
Time is running out
And indeed with its blog post announcement of the 300 million milestone, Microsoft took the opportunity to remind folks that "time is running out" on the freebie offer, and those who don't upgrade before or on July 29 will have to pay $119 (around £82) for Windows 10 Home.
Whether Windows users need a reminder is just a tad debatable though, given the amount of badgering those on Windows 7/8.1 have been on the receiving end of since the launch of the newest version of Windows.
Microsoft also shared a number of fun facts – well, facts, anyway – and stats gleaned from Windows 10 users (another ripe source of controversy).
These include the fact that Cortana on Windows 10 has now answered over 6 billion queries, and over 63 billion minutes were spent surfing with Microsoft Edge in March, which represents a 50% growth in usage time since the last quarter.
Windows 10 users are also playing more games than ever, Microsoft notes, with over 9 billion hours of gameplay having been racked up since the OS was launched (with DX12 support, of course).
- Check out our experiences with Windows 10
Get daily insight, inspiration and deals in your inbox
Get the hottest deals available in your inbox plus news, reviews, opinion, analysis and more from the TechRadar team.
Darren is a freelancer writing news and features for TechRadar (and occasionally T3) across a broad range of computing topics including CPUs, GPUs, various other hardware, VPNs, antivirus and more. He has written about tech for the best part of three decades, and writes books in his spare time (his debut novel - 'I Know What You Did Last Supper' - was published by Hachette UK in 2013).