How to use Activity Monitor on a Mac

2 min read · 7 steps · Updated 2 October 2026

Short answer

Open Activity Monitor from Applications, Utilities, or search for it with Spotlight. The tabs CPU, Memory, Energy, Disk and Network show what each app is using right now. Click a column heading to sort, and select an app and click the stop button to quit one that has hung.

Activity Monitor is the Mac's counterpart to the Windows Task Manager. It answers the questions behind most performance complaints: which app is keeping the processor busy, which one is eating memory, and what is draining the battery.

Menu names are from recent versions of macOS, where the settings app is called System Settings.

Step by step

  1. Open Activity Monitor

    Press Command + Space, type Activity Monitor and press Return. The app is in Applications, Utilities.

  2. Look at the CPU tab

    Click the % CPU column to put the busiest process at the top. An app that stays high when you are not using it may be stuck. The value can go above 100 percent, because each processor core counts as 100.

  3. Look at the Memory tab

    The Memory Pressure graph at the bottom matters more than the numbers. Green is fine. Yellow or red means the Mac is short of memory and is slowing down: close apps and browser tabs.

  4. Look at the Energy tab

    On a MacBook, Energy Impact and the 12 hr Power column show which apps have used the most battery.

  5. Look at Disk and Network

    They show how much each process reads, writes, sends and receives. This is where you see what is busy when the Mac seems to work by itself.

  6. Find a process

    Type a name in the search field at the top right. The View menu switches between All Processes, My Processes, Windowed Processes and other groups.

  7. Quit a hung app

    Select the process and click the stop button, the X in a circle, in the toolbar. Choose Quit first. Use Force Quit only if that does not work, because unsaved changes are lost.

Good to know

Leave alone anything you do not recognise that belongs to the user root or to the system, such as kernel_task or WindowServer. They are parts of macOS.

Double-click a process to see details about it.

A quicker way to end one frozen app: how to force quit a frozen app on a Mac.

What to do with what you find: Mac running slow: 8 fixes to try and MacBook getting hot: 7 things to check.

In short: Open Activity Monitor, sort by % CPU, check Memory Pressure, Energy on a MacBook, search for a process, stop button to quit a hung app.

Sources
  • Apple Support: View information about Mac processes in Activity Monitor

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