Find your computer's uptime in seconds
Your computer tracks how long it has been running since the last restart or shutdown. This number is called uptime. On Windows, you can see it in Task Manager or System Information. On Mac, it appears in About This Mac. On Linux, the command line shows it when ready. The method depends on your operating system, but all three take less than a minute.
Knowing your uptime matters for a few reasons. If your computer has been on for weeks without restarting, it may run slower or use more memory. If it keeps restarting on its own, that signals a problem worth investigating. If you are troubleshooting a crash or freeze, uptime tells you whether the issue happened right after startup or after days of continuous use.
Key Takeaways
- Windows users can open Task Manager and look at the Performance tab to see uptime in real time.
- Mac users can click the Apple menu, select About This Mac, and read the uptime line directly.
- Linux users can type uptime in the terminal to see how long the system has been running.
- A computer that has been on for weeks without restarting may slow down and benefit from a restart.
- Unexpected restarts or very short uptime can point to hardware problems or software conflicts that need attention.
Check uptime on Windows using Task Manager
Open Task Manager by pressing Ctrl + Shift + Esc, or right-click the taskbar and select Task Manager. Click the Performance tab at the top. In the left sidebar, click CPU. At the bottom of the window, you will see a line that says "Up time" followed by a duration in days, hours, minutes, and seconds.
If Task Manager does not show uptime on the Performance tab, your Windows version may be older. In that case, right-click the Start button, select System, and look for "System uptime" in the About section. Some older Windows versions require you to open Command Prompt and type systeminfo | find "System Boot Time" to see when the computer last started.
Check uptime on Mac using About This Mac
Click the Apple menu in the top-left corner of the screen. Select About This Mac. A window opens showing your Mac model, processor, memory, and other details. Look for a line that says "Time since last restart" or straightforward "Uptime." The duration appears in days and hours.
If you do not see uptime in About This Mac, you can also check it in System Preferences. Open System Preferences, click General, and scroll down to find the uptime information. On newer Macs running macOS Ventura or later, the path may be System Settings instead of System Preferences, but the information is in the same General section.
Check uptime on Linux using the terminal
Open a terminal window. Type the command uptime and press Enter. The output shows how long the system has been running, the current time, how many users are logged in, and the system load average. The uptime appears at the beginning of the line and is formatted as days, hours, and minutes.
If you want more detailed information about when the system last booted, type last reboot in the terminal. This shows a log of recent restarts with timestamps. You can also use who -b to see just the boot time in a simpler format.
What long uptime means for your computer's performance
A computer running for weeks or months without a restart will eventually slow down. Memory leaks—where programs fail to release memory they no longer need—accumulate over time. Temporary files pile up. Background processes may use more resources than they did at startup. A restart clears memory, closes stray processes, and gives your system a fresh start.
If your uptime is very short—a few hours or less—and you did not restart intentionally, your computer may be restarting on its own. This can happen because of Windows updates, driver problems, overheating, or hardware failure. Check your system logs to see whether restarts are scheduled or unexpected. If restarts keep happening without your input, that is worth investigating before it causes data loss.
When to restart your computer
Most people do not need to restart every day. If your computer is running smoothly and you are not experiencing slowdowns, a weekly or monthly restart is fine. However, if you notice lag, freezing, or programs crashing, a restart often fixes it. After installing major updates—especially Windows or security patches—a restart is usually required and will happen automatically.
If you work with large files, run memory-intensive programs like video editing software, or leave your computer on 24/7, restarting every week or two keeps performance steady. Servers and always-on machines benefit from a scheduled restart during off-hours. For everyday use, restart whenever you notice slowness, or at least once a month as routine maintenance.
Frequently Asked Questions
Why does my uptime reset to zero?
Uptime resets whenever your computer restarts or shuts down completely. Windows updates, power outages, accidental shutdowns, and sleep mode do not reset uptime—only a full restart does. If your uptime keeps resetting unexpectedly, your computer may be restarting automatically due to updates, driver crashes, or hardware problems.
Does sleep mode affect uptime?
No. Sleep mode pauses your computer but does not restart it, so uptime keeps counting. Hibernation also does not reset uptime. Only a full shutdown or restart resets the counter to zero.
What is a normal uptime for a home computer?
There is no single normal uptime. Some people restart daily, others go weeks without restarting. If your computer runs smoothly, any uptime is fine. If you notice slowness, lag, or crashes, a restart usually helps regardless of how long it has been running.
Can I see uptime history, or just the current uptime?
Most operating systems show only the current uptime since the last restart. To see a history of restarts and when they happened, check your system logs. On Windows, open Event Viewer and look at the System log. On Mac, check the Console app. On Linux, use the last reboot command.