The quickest way to check your operating system

The fastest way to find your operating system depends on what device you have. On Windows, press the Windows key and the Pause/Break key together, or right-click "This PC" on your desktop and select Properties. On a Mac, click the Apple menu in the top-left corner and choose "About This Mac". On Linux, open a terminal and type uname -a, then press Enter. You will see your operating system name and version number within seconds.

If you cannot find these buttons or menus, your device manufacturer may have moved them slightly. The method still works — you are just looking in a slightly different place on your specific model.

Key Takeaways

  • Windows users can find their operating system by pressing Windows key + Pause/Break, or by right-clicking "This PC" and selecting Properties.
  • Mac users should click the Apple menu in the top-left corner and choose "About This Mac" to see their operating system version.
  • Linux users can open a terminal and type uname -a to display their operating system information.
  • Your operating system version number matters for security updates and software compatibility, so write it down when you find it.

Finding your Windows version and build number

Windows shows you more detail than just the name. When you open the Properties window, you will see "Edition" (like Windows 11 Home or Windows 10 Pro), "Version", and "OS Build". The build number is a long string of digits — for example, 22621 — and it tells you exactly which security patches you have installed. This matters because two computers running "Windows 11" can have very different security protections depending on their build number.

You can also reach this same information by typing "winver" into the search box at the bottom of your screen and pressing Enter. A small window will pop up showing your edition, version, and build number all at once.

If you see a message saying your Windows version is no longer supported, that is a sign you need to update soon. Microsoft stops releasing security patches for older versions, which leaves your computer more vulnerable to attacks.

Finding your Mac version and build information

The "About This Mac" window shows your operating system as "macOS" followed by a name and number — for example, macOS Sonoma 14.1. The name (Sonoma, Ventura, Monterey) changes with major updates, while the number (14.1, 13.5) tracks smaller updates within that version. Both pieces of information matter: the name tells you how old your system is, and the number tells you whether you have the latest security patches.

In the same window, you will also see your Mac model (MacBook Pro, iMac, Mac mini), the processor type (Apple Silicon M1, M2, or Intel), and how much memory your computer has. If you ever need to buy software or ask for technical support, this window has almost everything someone will ask you for.

You can also check for updates in the same window by clicking "Software Update". If updates are available, macOS will show you what version you can update to and how large the read is.

Finding your Linux distribution and kernel version

Linux is different from Windows and macOS because it comes in many flavors, called distributions. Ubuntu, Fedora, Debian, and Linux Mint are all Linux, but they are different distributions with different tools and update schedules. When you type uname -a in a terminal, you see the kernel version (the core of the operating system), but not necessarily which distribution you are running.

To find your specific distribution, type cat /etc/os-release in the terminal. This shows you the distribution name, version, and other details. If that command does not work, try lsb_release -a instead. Different distributions use different methods, but one of these two commands will work on almost any Linux system.

The kernel version and distribution version are both important for security. Your distribution maintainer releases security patches on their own schedule, separate from the Linux kernel updates. Knowing both numbers helps you understand when your next security update is likely to arrive.

Why your exact version number matters for security

When a security vulnerability is discovered, the people who make your operating system release a patch — a small update that fixes the problem. But they only release patches for recent versions. If you are running Windows 10 build 19041 and a new vulnerability is found, Microsoft may have already stopped releasing patches for that build and moved on to newer ones.

This is why knowing your exact version and build number is important. If you see that your build number is several months old, or if you see a notification that your version is no longer supported, that is a signal to update. Updating is usually free and takes 15 minutes to an hour, depending on how many patches have accumulated.

You should check your operating system version at least once every few months, or whenever you see a notification about updates. If you have automatic updates turned on (which is the default on most systems), your computer will handle most of this for you — but it is still worth knowing what version you are running.

What to do if you cannot find your operating system information

If the standard methods do not work, your computer may be very old, heavily customized, or running a version you did not install yourself. If you bought the computer used, it might be running a version the previous owner set up.

Try these backup methods: On Windows, open Command Prompt (search for "cmd" in the search box) and type systeminfo, then press Enter. On Mac, if "About This Mac" does not open, restart your computer and try again — sometimes the menu is temporarily hidden. On Linux, if neither command works, try cat /proc/version in the terminal.

If none of these work, you may need to contact the person or company who sold you the computer, or take it to a local repair shop. They can tell you what you are running and whether it is still receiving security updates.

Frequently Asked Questions

Does it matter if I am on the latest version?

Yes, especially for security. Older versions stop receiving patches, which means new vulnerabilities will not be fixed. You do not need the absolute newest version, but you should not be more than one or two versions behind. Check your version now and plan to update if you are significantly older.

Can I change my operating system after I buy a computer?

Yes, but it is complicated and risky if you have never done it before. You can install Windows on a Mac or Linux on a Windows computer, but you will lose your current files and programs unless you back them up first. Most people keep the operating system that came with their computer.

What if my computer says it cannot update to the newest version?

Some older computers cannot run the newest operating systems because they lack the required processor or memory. In that case, you should update to the newest version your computer can run, and plan to replace the computer within a few years. Staying on an unsupported version leaves you vulnerable.

Is there a difference between "version" and "build number"?

Yes. The version is the major release (Windows 11, macOS Sonoma), while the build number is a specific snapshot of that version with particular patches included. Two computers with the same version can have different build numbers if one has been updated more recently.

Do I need to write down my operating system information?

It is helpful to write it down or take a screenshot. If your computer stops working and you need to call for support, or if you want to buy software that requires a specific version, having this information ready saves time. You can also email it to yourself as a note.