Why you might want to know your computer's uptime
Uptime is how long your computer has been running without a restart or shutdown. Knowing this number tells you whether your machine has been on for a few hours, a few days, or much longer. This matters because computers that run for weeks without restarting sometimes slow down, use more power, or develop temporary glitches that a restart fixes.
You might check uptime to troubleshoot a problem — if your computer has been on for 45 days, a restart is often the first thing to try. Or you might check it out of curiosity, or to see whether someone else has been using your machine while you were away. The method you use depends on whether you have a Windows PC, a Mac, or a Linux computer.
Key Takeaways
- On Windows, open the Task Manager by pressing Ctrl+Shift+Esc, click the Performance tab, and look for "Up time" in the CPU section.
- On a Mac, click the Apple menu, select About This Mac, click System Report, and find "System Boot Time" in the Software section.
- On Linux, open a terminal and type uptime to see how long the system has been running.
- If your computer has been on for more than a week or two and you notice slowness, a restart often solves the problem.
- Uptime resets to zero every time you restart or shut down your computer.
Checking uptime on Windows 10 and Windows 11
The fastest way on Windows is through the Task Manager. Press Ctrl+Shift+Esc at the same time to open it directly. If that does not work, right-click the taskbar at the bottom of your screen and select Task Manager from the menu.
Once Task Manager opens, click the Performance tab at the top. On the left side, click CPU. On the right side of the window, look for a line that says Up time. The number next to it shows how long your computer has been on — it will look something like "2 days, 5:47:23" or "18:32:45" for hours and minutes.
If you do not see the Performance tab, your Task Manager may be in a simplified view. Click "More details" at the bottom left to expand it, then follow the steps above.
Checking uptime on Mac
On a Mac, the process takes a few more clicks. Click the Apple menu in the top left corner of your screen, then select About This Mac.
A window will open. Click the System Report button at the bottom right. A new window appears with many technical details. In the left sidebar, make sure you are in the Software section. Scroll down in the right panel until you find System Boot Time. This shows the exact date and time your Mac last started up. To calculate how long it has been on, subtract that time from the current time.
If you prefer a quicker method, you can also open Activity Monitor (search for it in Spotlight by pressing Command+Space), click the System Memory tab, and look at the bottom of the window for uptime information, though the detail level is less precise.
Checking uptime on Linux
Linux users have the simplest route. Open a terminal window — the exact method depends on your Linux distribution, but usually you can right-click the desktop and select "Open Terminal" or search for Terminal in your applications menu.
Type the word uptime and press Enter. The terminal will display output that looks something like this: "10:45:32 up 7 days, 3:22, 2 users, load average: 0.15, 0.18, 0.16". The part that matters is "up 7 days, 3:22" — that means the system has been running for 7 days and 3 hours, 22 minutes.
What a long uptime means for your computer
If your uptime is measured in weeks or months, your computer is working hard without a break. This is not necessarily a problem — servers and some work computers run for months at a time. But for personal computers, long uptimes sometimes lead to slower performance, higher memory usage, or programs that behave oddly.
A restart clears temporary files from memory, closes background processes that may have accumulated, and refreshes your system. If you notice your computer is sluggish and the uptime is more than two weeks, try restarting and see whether things improve. You do not need to shut down every night, but restarting once a week or two is a good habit for most people.
How to restart your computer properly
On Windows, click the Start button, click the Power icon, and select Restart. On a Mac, click the Apple menu, select Shut Down, and check the box that says "Reopen windows when logging back in" if you want your programs to return to where you left them.
On Linux, open a terminal and type sudo reboot, then press Enter. You may be asked for your password. The system will restart automatically.
After your computer restarts, the uptime will reset to zero (or a few minutes, depending on how long startup takes). If you check uptime again using the methods above, you will see a much smaller number.
Frequently Asked Questions
Does uptime include time when my computer is in sleep mode?
No. Sleep mode pauses your computer but does not count toward uptime. Only time when your computer is fully powered on and running counts. If your computer has been asleep for 8 hours, that time does not add to the uptime number.
What if I see a very high uptime but I know I restarted recently?
This usually means your computer went into sleep mode instead of shutting down, or you restarted a program rather than the whole system. Check that you selected Restart (not Sleep) and waited for the shutdown to complete. If the uptime is still wrong, a full shutdown and power-on may be needed.
Can I check uptime on my phone or tablet?
Yes, but the process is different. On iPhone or iPad, go to Settings, Battery, and look for "Time on Battery" or "Time Since Last Charge." On Android, go to Settings, About Phone, and look for "Uptime" or "Time Since Boot." These show how long the device has been on since the last restart.
Is it bad to leave my computer on all the time?
Leaving it on constantly uses more electricity and can shorten the lifespan of some components, especially the power supply and cooling fans. For most home users, shutting down at night or restarting once a week is a good balance between convenience and hardware longevity.