How to show CPU and memory usage in the Mac menu bar

Why you’d want the numbers in the menu bar

A Mac that suddenly feels slow, a fan that spins up, a MacBook that’s warm on your lap with nothing open — each time the first question is the same: is something working hard, and what? Activity Monitor answers it, but only once you’ve stopped, opened it and gone looking. By then whatever was busy may have finished.

A number in the menu bar answers it at a glance, while it’s happening. Over a few days it also teaches you what normal looks like on your own Mac, which is what makes an unusual number stand out.

Where macOS shows CPU and memory today

Activity Monitor. Open it from Applications → Utilities, or search for it with Spotlight. The CPU tab lists every app and process by how much processor time it’s using; the Memory tab lists them by memory. Click a column heading to sort by it, so the busiest is at the top.

A graph in the Dock. With Activity Monitor open, choose View → Dock Icon and pick Show CPU Usage or Show CPU History. Its Dock icon becomes a small live graph — visible whenever the Dock is, as long as Activity Monitor stays open.

A floating window. Window → CPU Usage and Window → CPU History open small windows of their own that you can leave in a corner of the screen while you work.

Terminal. Type top -o cpu and press Return for a live list sorted by CPU use; press q to leave. It’s the same information as Activity Monitor, in text.

None of these is in the menu bar, and all of them depend on an app being open and on screen.

Reading the CPU number

Over 100% is normal. In Activity Monitor, 100% means one processor core fully busy, so an app using several cores at once can show 200%, 400% or more. The figures at the bottom of the CPU tab — System, User and Idle — describe the whole processor, and Idle is the share with nothing to do.

Short spikes are normal too. Opening an app, loading a page or exporting a file sends CPU use up for a moment. What’s worth noticing is a high number that stays high while you aren’t doing anything.

Names you’ll see near the top. kernel_task is macOS itself; Apple explains that it takes CPU time on purpose when the Mac is warm, to keep the temperature down, so a busy kernel_task is a sign of heat rather than the cause of it. WindowServer draws everything on screen and works harder with more displays and more moving windows. mds and mdworker are Spotlight indexing, which runs hard after a macOS update or when lots of new files arrive, and settles on its own. Browser helper processes are usually individual tabs or extensions.

Reading the memory number

A full-looking memory number is not a problem by itself. macOS uses memory that apps don’t need to keep recently used files ready, because unused memory does nothing for you. That’s why Memory Used can look high on a Mac that runs perfectly well.

Memory Pressure is the number that matters. At the bottom of Activity Monitor’s Memory tab, the Memory Pressure graph is green while there’s enough, and turns yellow and then red when the Mac is working to make room. Swap Used beside it shows how much the Mac has moved out to the disk; a large and growing figure means it has been short of memory.

What helps when it’s short. Quit the apps you aren’t using — or have the apps you pick quit on their own after sitting unused for a while. Close tabs you’re keeping open “for later”. If one app’s memory keeps climbing the longer it runs, quitting and reopening that app usually resets it.

CPU and memory in the menu bar with MacFixes

MacFixes’ Menu bar readouts put CPU and memory in the menu bar as live numbers, with no window to keep open. You can add battery and network speed beside them, and choose the order they sit in. Hold ⌘ and drag to move them along the menu bar like any other item.

On a MacBook the battery readout can show the time left instead of the percentage — the estimate macOS took out of the battery menu; here’s where else to find battery time remaining. The network readout shows your connection’s speed as it happens, which helps you tell whether a slow page is the Mac or the connection; internet speed in the menu bar is about that question.

The readouts don’t show temperatures; those are left out on purpose. And the fix needs no permission from macOS. When a number looks wrong, Activity Monitor is still the place to find out which app is behind it — the menu bar tells you when to look.

Permissions, and turning it off

More fixes macOS doesn’t give you

One of 47 fixes and 10 apps in MacFixes. Every fix · Every app · Something else your Mac won’t do? Request it.