John Taggart/Bloomberg via Getty ImagesWindows 10 is about to expire.In less than six months, 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: How to upgrade your 'incompatible' Windows 10 PC to Windows 11 nowHow is this even possible? It feels like only yesterday, but in fact, Windows 10 was officially released to the public nearly a decade ago, in July 2015. Following on the heels of the ill-fated Windows 8, it became an unqualified success among consumers and business customers alike. And it's continued to be insanely popular more than three years after the release of its successor, Windows 11.That's good news, right? Well, not exactly. Microsoft has a big challenge on its hands in the run-up to that end-of-support date: convincing its enormous installed base to leave their beloved Windows 10 behind and make the move to its successor operating system, Windows 11. To complicate things, they've departed radically from the normal upgrade rules.Also: Microsoft at 50: Its incredible rise, 15 lost years, and stunning comeback - in 4 chartsI wrote the original version of this post in July 2023, when that end date was more than two years in the future, and I've been revisiting the topic regularly to help answer some burning questions. When does Windows 10 support end? Like every version of Windows in the modern era, Windows 10 adheres to a 10-year support lifecycle. That means most Windows 10 editions -- Home, Pro, Pro Workstation, Enterprise, and Education -- will reach their end-of-support date on Oct. 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 will continue to work just as they always have, and they will do so indefinitely.Also: Windows 10 PC can't be upgraded? You have 5 options and 6 months to take actionFrom that date forward, however, those PCs will no longer receive security fixes through Windows Update unless their owners pay Microsoft for an Extended Security Updates (ESU) subscription. On Windows 10 PCs without an ESU subscription, any security flaws found from that day forward will remain unpatched, making those PCs increasingly vulnerable to online attacks.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 Oct. 14, 2025, along with the editions described earlier. The 2016 LTSB release ends support a year later, on Oct. 13, 2026. Beginning in 2019, the name changed to Long Term Servicing Channel (LTSC). For Windows 10 Enterprise LTSC 2019, the end date is Jan. 9, 2029.Confusingly, Windows 10 Enterprise LTSC 2021 has only a five-year support lifecycle, which means it ends support on Jan. 12, 2027. Show more 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: There's a quiet PC boom happening - thanks to Windows 10 and the tariffsOne of the sources I have relied on over the years is the US 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 Institutes of Health, the National Weather Service, the IRS, and NASA.I've been checking that source regularly over the past few years. When I visited DAP at the beginning of April 2025, I retrieved 90 days' worth of data, covering billions of visits to those websites from people using Windows computers, Macs, and mobile devices from all around the world. Here's what the data told me when I filtered it to show only visits from PCs running Windows 10 and Windows 11: Show more Windows 11 has steadily overtaken Windows 10 in visits to U.S. government websites as the deadline approaches.  DAP/ZDNETThat's a big improvement over an eight-month period. Last August, visits from PCs running Windows 10 significantly outpaced those from Windows 11. (In case you're curious, other versions of Windows represent a trivial share of visits, being outnumbered by every alternative desktop platform, including ChromeOS.) But if you extrapolate those numbers to the worldwide population of Windows PCs, you can see the problem. Over the past eight months, about 1.6% of Windows 10 PCs have been replaced by Windows 11 PCs each month. At that pace, about 35% of those 1.4 billion devices will still be running Windows 10 when October 2025 rolls around, and many of them have no supported upgrade path. Also: Windows 10 PC can't be upgraded? You have 5 options and 6 months to take actionFor people who are concerned about the security of the internet at large, that thought is -- well, let's call it unnerving. Another widely used measure of web traffic, StatCounter, offers its own estimates of traffic from PCs running Microsoft Windows. If you believe their charts, about 54% of PCs worldwide are still running Windows 10 as of April 2025. Now, I have my issues with StatCounter's metrics, a topic I have recently discussed at length. I think the StatCounter numbers probably overcount the number of Windows 10 PCs, but they do confirm the general conclusion that there will be a large number of unsupported PCs at the end of 2025. How many PCs will be running Windows 10 at the end of 2025? That's the real question, isn't it?Despite predictions of the imminent demise of the PC market, OEMs continue to sell more than 200 million new Windows computers each year. The most optimistic scenario is that every one of those new PCs sold in the next year replaces a Windows 10 device that is then retired, with another 100 million or so older PCs 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. The prospect of large tariffs on PCs manufactured in China and sold in the US complicates the equation considerably.Also: Can't quit Windows 10? You can pay Microsoft for updates after October, or try these alternativesIf the shift to Windows 11 continues at its current rate, as measured by the DAP data, roughly 35% of PCs will still be running Windows 10 in October 2025. That adds up to more than 500 million PCs that will be running an outdated, unsupported operating system at the end of the year.I suspect that pace will accelerate significantly, especially in enterprise deployments that have been planning for this transition for the past few years and will be executing on those plans before the end of 2025. Even at that accelerated pace, though, it will still mean hundreds of millions of PCs will be running Windows 10 when the end-of-support date rolls around. Yikes.Who owns those PCs?Those who don't qualify for an automatic 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 aren't ready to go through a wholesale Windows 11 migration. Many of them will use the normal upgrade cycle to perform that migration over time, and they have the option to pay for Windows 10 upgrades for up to three years after the end-of-support date.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. Show more Will Microsoft extend the support deadline for Windows 10? I know some people are convinced this is 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, Microsoft issued emergency security updates for Windows 7 in 2021 after its support had officially ended.Of course, in both 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: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.Also: Can you still get a Windows 10 upgrade for free in 2025? Short answer: MaybeFor 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 "incompatible" 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 may not even realize that the option is available. 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.Nothing in the company's behavior over the past year suggests they have any plans to extend the support deadline for Windows 10.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. However, 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 cyberattack 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.That incident was a PR nightmare for Microsoft, and a repeat would be even more devastating to the company's reputation. That's why Microsoft has offered paid options to extend support for Windows 10 by three years. Customers in enterprise and education deployments are likely to take advantage of those options.Consumers have the option to pay for updates for a year. I predict that few will do so. After that? Well, you're on your own. Show more This article was originally published in July 2023. The most recent update was in April 2025.Get the morning's top stories in your inbox each day with our Tech Today newsletter.Windows