In recent public filings, Microsoft has said there are roughly 1.4 billion Windows PCs worldwide. If three-quarters of them are still running Windows 10, that's a billion PCs or so, all running an operating system that will hit its end of life in two years.

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Windows 10 is about to expire.

In just over two years, Microsoft's most successful operating system release ever will reach its end-of-support date. Like Monty Python's Norwegian Blue, it will be pushing up the daisies. It will have shuffled off its mortal coil, run down the curtain, and joined the bleedin' choir invisible!

Also: When will Microsoft end support for your version of Windows or Office?

How is this even possible? It feels like only yesterday, but in fact, Windows 10 was officially released to the public eight years ago this month, in July 2015. Following on the heels of the ill-fated Windows 8, it became an unqualified success among consumers and business customers alike.

That's good news, right? Well, not exactly.

Microsoft has a big challenge on its hands in the next two years: convincing its enormous installed base to leave their beloved Windows 10 behind and make the move to its successor operating system, Windows 11.

As the clock ticks down to that end date, I know many of you have questions, so I did some digging.

When does Windows 10 support end, and what does that mean for Windows 10 users?

Like every version of Windows in the modern era, Windows 10 adheres to a 10-year support lifecycle. That means that most Windows 10 editions -- Home, Pro, Pro Workstation, Enterprise, and Education -- reach their end-of support date on October 14, 2025. (For the nerdy details on how that date is calculated, see "When will Microsoft end support for your version of Windows or Office?")

So, what happens when that day arrives? Nothing. Seriously, absolutely nothing happens on that date. PCs running Windows 10 continue to work just as they always have, and they will do so indefinitely. From that date forward, however, those PCs will no longer receive security updates. Any security flaws found from that day forward will remain unpatched, making those PCs increasingly vulnerable to online attacks.

Also: Is Microsoft cracking down on Windows 11 updates for unsupported hardware?

There is at least one exception to this cutoff date, which applies to PCs running Windows 10 Enterprise Long Term Servicing editions. In all, Microsoft has released four of these editions. The 2015 Long Term Servicing Branch (LTSB) ends support on October 14, 2025, along with the editions described earlier. The 2016 LTSB release ends support a year later, on October 13, 2026. Beginning in 2019, the name changed to Long Term Servicing Channel (LTSC). For Windows 10 Enterprise LTSC 2019, the end date is January 9, 2029. Confusingly, Windows 10 Enterprise LTSC 2021 has only a five-year support lifecycle, which means it ends support on January 12, 2027.

How many PCs are running Windows 10 today?

If anyone tells you they know the answer to this one, maybe stop listening to them?

Microsoft can probably make a solid estimate based on its telemetry, but the rest of us are forced to guess based on fragmentary third-party metrics.

Also: How to screen record in Windows 10 or Windows 11

One of the sources I have relied on over the years is the United States Government's Digital Analytics Program (DAP), which has a well-organized repository of information about traffic to official websites run by agencies like the Postal Service, the National Weather Service, the IRS, and NASA.

When I visited DAP last week, I had no trouble downloading data from the last 90 days, summarizing more than 1.6 billion visits to those websites from people using Windows-based PCs from all around the world. Here's what the data told me:

See what's missing from this table?

DAP/

Notice anything missing from that table? Yeah, there's no mention of Windows 11, which seems more than a little odd given that Microsoft's OEM partners have sold hundreds of millions of PCs running Microsoft's latest operating system in the past two years. The problem? Windows reports itself to analytics programs using the same identification string as Windows 10. Which means that as far as most web analytics measurements are concerned, Windows 10 and Windows 11 are the same operating system.

To the folks who run official websites for the US Government, this question is mostly academic. It's probably enough to know that some fairly large percentage of visitors are using Windows PCs and that only a minuscule fraction of them are using older versions.

Also: Windows 10 is a security disaster waiting to happen. How will Microsoft clean up its mess?

But for people who are concerned about the security of the Internet at large, the thought that some very large number of devices will soon be running an unsupported and increasingly insecure operating system is ... well, let's call itunnerving.

Another widely used measure of web traffic, StatCounter, claims it can properly sort traffic from PCs running Windows 10 and Windows 11. Here's their graph of web traffic from Windows PCs in their network over the past year.

Stat Counter/

That purple line at the top of the chart is Windows 10, and the blue line far below it is Windows 11. Now, I have my issues with StatCounter's metrics, a topic I have not been shy about discussing over the years. But I think the broad strokes of this data are probably accurate. The current installed base of Windows PCs consists of about three times more PCs running Windows 10 than its successor.

In recent public filings, Microsoft has said there are roughly 1.4 billion Windows PCs worldwide. If three-quarters of them are still running Windows 10, that's a billion PCs or so, all running an operating system that will hit its end of life in two years.

How many PCs will still be running Windows 10 in two years?

That's the real question, isn't it?

After two pandemic-fueled years of hypergrowth, the PC market is finally beginning to slow, but it's likely that more than 200 million new Windows PCs will be sold each year for the foreseeable future. The most optimistic scenario is that every one of those new PCs replaces a Windows 10 device that is then retired, with another 100 million or so replaced by Chromebooks, iPads, and Macs, Maybe some old PCs are simply put out to pasture and not replaced at all, as consumers decide to use their phones or tablets instead.

Also: The best computers: Comparing laptops, Macs, PCs and more

That best-case scenario still leaves hundreds of millions of people still running Windows 10 when the October 2025 end-of-support date rolls around. Who owns those PCs?

• Those who can't upgrade. Some people own older hardware that doesn't meet the minimum hardware compatibility standards for Windows 11. Basically, that means any PC that was designed in 2018 or earlier. Note that this category includes many budget PCs that used older designs and unsupported CPUs but were sold as new in 2019 and 2020.

• Corporate PCs that are standardized on Windows 10. A nontrivial number of enterprise IT managers have just finished their Windows 10 migrations in the last year or two and probably aren't anxious to do it again.

• Windows 10 diehards. From my time spent reading support forums, I know there's a large population of longtime Windows users who are unhappy about the changes in Windows 11. Some of them will reluctantly upgrade, but others won't.

Will Microsoft extend the support deadline for Windows 10?

There's certainly a possibility, and there's precedent for it in the experience of Windows XP, which ended support in April 2014, more than 12 years after it was first released. Windows XP users even received emergency security updates well after that official end date, to address the WannaCry vulnerability in 2017 and a similar flaw in 2019.

Likewise, Windows 7 holdouts received an option to pay for Extended Security Updates for three full years after the official end of support in January 2020.

Of course, in both of those cases, the customers running the soon-to-be-obsolete Windows version had the option to upgrade to a new version. Indeed, that's the recommendation from Microsoft's official Product End of Support page:

Also: The best Windows laptop models: Comparing Dell, Samsung, Lenovo, and more

Once a product reaches the end of support, or a service retires, there will be no new security updates, non-security updates, or assisted support. Customers are encouraged to migrate to the latest version of the product or service.

For Windows 10, though, that alternative might not be available. Devices that don't meet the hardware compatibility requirements will have no Microsoft-supported migration path to a newer version. As I pointed out the last time I looked at this issue, the owners of those perfectly functional PCs, some only five or six years old, will instead have the following options:

• Install a non-Microsoft operating system. Maybe 2026 will be the year when desktop Linux finally takes hold, although that's unlikely. ChromeOS Flex might be another option, but it has its own hardware compatibility requirements that probably make it unsuitable for older hardware.

• Ignore Microsoft's warnings and upgrade to Windows 11 anyway. There are options to install Windows 11 on unsupported hardware, but they require a fair amount of technical experience. People who are clinging to old PCs because they can't afford a new one likely don't have those specialized skills. and I doubt that many businesses would be willing to risk the support issues that come with that approach.

• Keep running Windows 10 and hope for the best. History suggests that this is the most likely option.

Microsoft and its OEM partners would prefer that the owners of those devices dump them in a landfill and buy a new PC running Windows 11. But my experience with PC owners, especially older people on a fixed income, is that they will use those devices until they stop working. Those PCs will be sitting ducks for a cyber attack like WannaCry, which was brutally effective against the large population of Windows 7 PCs that were still in use three years after its support ended.

Also: Microsoft to Windows 10 users: No more feature updates for you

That incident was a PR nightmare for Microsoft, and a repeat would be even more devastating to the company's reputation. That's why I suspect Microsoft will extend support for Windows 10 by at least a year or two, especially for enterprise customers.

Given the fundamental similarities between Windows 10 and Windows 11, it probably wouldn't be much of a technical burden, and the costs of doing nothing are simply too high

Windows 10

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• The top Windows laptops compared
• How to recover deleted files in Windows 10 or 11
• Here's how you can still get a free Windows 10 upgrade
• Windows 11 setup: Which user account type should you choose?
• How to run a Windows app on Linux with Wine