Microsoft stopped offering a free upgrade to Windows 10 at the end of last month and, according to Netmarketshare, it's now on roughly 21 percent of the world's PCs - a definition that includes Macs and Linux boxes.
Is that good or not? It depends what you expected. Around a million people per day switched to Windows 10, or 116,000 per second, which sounds pretty impressive.
In terms of reaching Microsoft's target of a billion copies of Windows 10 in three years, it's slightly ahead of target. However, Microsoft accepts that it's not going to make that. Its projections included Windows 10 running on Xbox One games consoles, smartphones and "internet of things" devices in volumes it won't meet.
Windows 10 has also met my predictions. In early February, I wrote that "If all goes well, it could hit 20 percent by the time Microsoft stops offering free upgrades at the end of July. For the July numbers, published on August 1, I'd regard 25 percent as a spectacular success, and 30 percent as extremely unlikely."
Given the likely percentage errors in Netmarketshare's numbers, there's no significant difference between my 20 percent guesstimate and the reported 21.13 percent.
I also suggested that "Windows 10 could make 30 percent by Christmas, depending on whether Microsoft offers a good upgrade deal, and the general health of the PC market." I'm not so sure about that now.
Of course, prediction is difficult, especially about the future. But there's no good upgrade deal, and there are too many unknowns.
First, we don't know how big a kick Windows 10 got from last-minute installations, which have yet to be fully reflected in Netmarketshare's numbers. This could result in Windows 10 jumping to around 23 percent next month.
Second, Microsoft has allowed more generous loopholes than I expected. I assumed - wrongly - that Microsoft would turn off the activation servers to stop the free upgrades. Instead, it allowed people to complete the upgrade if they started it before the deadline. It has also allowed people to upgrade after the deadline by using Windows 7/8.x product keys. (This won't last forever.) It has even left a loophole in continuing the free upgrade for people who use assistive technologies such as screen readers.
Third, the PC market may yet pick up for Christmas. PC sales actually grew in North America in this year's second quarter, for the first time in five quarters. IDC reported a 4.9 percent increase, compared with the same quarter last year, while Gartner reported a 1.4 percent increase. This was despite a fall in Apple's US sales, by 9.3 percent (according to Gartner) or by 7.6 percent (according to IDC). Dell, HP, Lenovo and Asus all enjoyed better Q2 sales
Of course, US growth is not global growth. "However," said IDC, "the strong results in the US offer a glimpse of what the market could look like with pockets of growth and a stronger overall environment. It's not dramatic growth, but it could push the market into positive territory slightly ahead of our forecast for 2018."
Fourth, most of the free upgrades to Windows 10 were installed on consumer devices, not on business PCs.
The future growth of Windows 10's installed base will depend partly on what businesses do, and most companies take a long time to upgrade their fleets of PCs. A few are early adopters, but in general, I reckon it takes a large enterprise about 18 months to plan a PC upgrade and another 18 months to complete it. Some companies will need to start now to be sure they'll finish by the time Windows 7 becomes unsupported on January 14, 2020.
At least one organization - the UK police - is still upgrading from Windows XP to Windows 8.1, which may well cost British taxpayers barrels of money. The police are paying Microsoft for continued XP support, and they will have to pay the overheads for two OS upgrades instead of one.
A rational organisation would have upgraded to Windows 7 Pro (which included a free XP Mode) as soon as possible after its launch in 2009. They would then have enjoyed up to 11 years of Windows 7's obvious benefits, followed by a simple upgrade to Windows 10. And staff wouldn't have to learn both Windows 8.1 and Windows 10.
You'd think companies that suffered from delaying the XP upgrade - when rushed jobs pushed up costs - would want to avoid making the same mistake again with Windows 7. Indeed, they should be keen to move to Windows 10, because it removes the need for "big bang" upgrades every few years.
However, according to Netmarketshare, Windows 7 still has 47 percent of the market. It will need to keep falling at around one point per month if the industry is going to make it.
None of this means that I necessarily believe Netmarketshare's numbers for PC market shares: I certainly don't believe some of the monthly totals. I'm mainly watching the rate at which the numbers are changing, and in which direction, over six to 12 months or so.
If you want different numbers, based on website usage rather than unique visitors, StatCounter reckons that Windows 10 grew from zero to 24 percent market share in its first year, while Windows 7 fell from 55 to 41 percent. If true, there are only 17 points between the two operating systems, rather than the 26 points on Netmarketshare's numbers.
All these numbers are for the global market, but not all countries are the same.
In North America, for example, StatCounter puts Windows 7 on 32.5 percent and Windows 10 on 27.6 percent for July 2016. On that basis, American Windows 10 should overtake Windows 7 well before Christmas. On StatCounter's UK numbers, it already has.
If true, it's remarkable for an operating system to go from nothing to market leader in one year.