"Active devices" mean devices than have been active in the past 28 days, Microsoft officials have said. The figure includes not only Windows 10 installed on PCs, tablets and phones, but also on Xbox One consoles and HoloLens, Surface Hubs.
Today's blog post announcing the latest milestone also includes a reminder to users that Microsoft's first-year-free upgrade offer for Windows 10 ends on July 29, 2016. Just a reminder: The first-year-free upgrade deal means those running Windows 7, 8.X and Windows Phone 8.1 can upgrade to Windows 10 for free. It doesn't mean those who upgraded for free start having to pay for Windows 10 after July 29.
Today's blog post seems to imply that Microsoft has decided definitively against extending its first-year free offer. It says:
"After July 29th, you'll be able to continue to get Windows 10 on a new device, or purchase a full version of Windows 10 Home for $119." (The $119 price is the current retail price of a copy of Windows 10 Home.)
However, this reminder doesn't necessarily mean Microsoft has decided against renewing that deal, a company spokesperson said when I asked.
The full official statement to my question as to whether Microsoft plans to extend the free upgrade deal (which doesn't really answer it):
"The free upgrade offer has been a big success, leading to the fastest adoption of Windows ever, with Windows 10 on more than 300 million active Windows devices. The free upgrade promotion is currently slated to end on July 29 and we encourage all of our customers to take advantage of it while it is still active."
(Note the words "currently slated." That's the iffy part.)
Microsoft might end up making its Windows 10 Anniversary Update (a k a Redstone 1), due around July 29, free for the first year as a way of extending the offer, as some have suggested. Or it could opt for a low-price, but not totally free upgrade offer to take its place -- if officials decide that keeping some kind of upgrade offer in place makes sense.
Update (2 pm ET on May 5): Microsoft is amending the statement the company sent me to note that: "The free upgrade promotion is ending on July 29 and we encourage all of our customers to take advantage of it while it is still active."
Although Microsoft told me earlier that the company was not drawing a line in the sand today and stating definitively that the free upgrade offer would end July 29, a spokesperson said the original information conveyed to me was incorrect. The free upgrade deal will end July 29.
I have to admit, I am surprised Microsoft is ending the promotion, given that the vast majority of users get a new version of Windows when they buy new PCs, and not by upgrading their existing OS. (In other words, I take any OEM claims of their businesses being hurt by the free upgrade deal with a very big grain of salt.) But I guess that's that....