600 Million (Premium)

Windows 10 usage has accelerated a bit in the past 6 months. Let's do some math.

Expect mistakes. Math is hard, especially when the numbers are fuzzy and when I'm in the driver's seat.

Microsoft this week revealed that there are now over 600 million Windows 10 PCs and devices worldwide. This is the first time since May that we've received an update on this usage figure. Back then, the tally was 500 million active Windows 10 PCs worldwide.

As you may know, I watch these numbers carefully: While there is always wiggle room and interpretation to be had, the active Windows 10 PC usage base is one of the very few "hard" numbers that Microsoft provides. That is, this number is real: It maps very closely, I think, to the actual real world number of users, and it represents real usages. It's not licenses sold, a nebulous figure at best.

That said, the number is also fuzzy because it includes non-PC devices like Xbox One consoles. I'll expand on that bit later, but it makes some calculations basically impossible.

Anyway, here's the math on Windows 10 usage, as I understand it. I'll keep using the term PCs here, but it's really "devices, mostly PCs."

100 million new active Windows 10 PCs in 6 months works out to about 16.7 million new active Windows 10 PCs per month.

That's a faster average monthly growth rate than during the previous known period, though these things are never directly comparable. Previous to May, Microsoft revealed in October 2016 that there were 400 million active Windows 10 PCs. So between October 2016 and May 2016, an average of 14 million new active Windows 10 PCs were added each month.

Looked at another way, from October 2016 to May 2017, a period of about seven months, Microsoft added 100 million new active Windows 10 PCs. It took the company only six months to add the next 100 million active Windows 10 PCs. And that, more recent, period did not include a holiday selling period. This further supports the notion that Windows 10 uptake is speeding up, I think.

Again, it's worth pointing out that not all of these PCs are technically PCs: The tally includes some tens of millions of Xbox One consoles, Lumia and other Windows phones, Surface Hubs, and other Windows 10-based devices. But Microsoft has acknowledged repeatedly that the vast majority of these are PCs. That was true even when the firm allegedly still thought Windows phone could survive. (And I've already debunked the notion that Windows phone's failure was some kind of a surprise to Microsoft.)

These are the major usage milestones for Windows 10:

April 2015. Microsoft's Terry Myerson makes the bold prediction that Windows 10 will be used on over one billion PCs within three years of its release, or roughly mid-2018.

July 2015. Microsoft releases the first version of Windows 10.

August 2015. 75 million active Windows 10 PCs.

January 2016. 200 million active Windows 10 PCs.

March 2016. 270 million active Windows 10 PCs.

May...