Press Esc while you hold down ⇧ Shift+Ctrl. Press Del while you hold down Alt+Ctrl, then click Task Manager. Type “task manager” into the Start search bar, then click the Task Manager app at the top of the results.

If you’re using Windows 7 or down, skip this step.

For example, an Up Time value of “01:16:23:21” would mean your computer has been on for one day, sixteen hours, twenty-three minutes, and twenty-one seconds without shutting down.