How to check CPU usage on a Mac

The quickest way to open Activity Monitor is the Spotlight shortcut: press Command and Space together, type "Activity Monitor", and press Return as soon as it appears. That is the Mac Activity Monitor shortcut most people use, since it is faster than digging through folders. If you would rather click, Activity Monitor lives in your Applications folder inside the Utilities subfolder, so open Finder, go to Applications, then Utilities, and double-click it there. That answers where Activity Monitor is on a Mac: it is a built-in utility, not something you install.

Once it is open, you can keep it in the Dock for next time by right-clicking its icon and choosing Options, then Keep in Dock. Activity Monitor is the Mac equivalent of Task Manager on Windows, and I have written a companion guide on finding and using the Task Manager on a Mac if it is the app itself you are looking for rather than how to read the CPU numbers.

In Activity Monitor, click the CPU tab along the top, then click the % CPU column header so the busiest process sits first. The % CPU column is the share of the chip each process is using, and the one thing that throws people is that a single process can read above 100 percent. That is because the figure is per core: a Mac with eight cores has 800 percent of CPU to give out, so a process using two cores flat out shows as roughly 200 percent. A reading over 100 is not a fault, it just means that process is spread across more than one core.

The bar along the bottom of the window is the whole-machine total, and it splits into three parts. System, in red, is the load from macOS itself and its background work. User, in blue, is the load from the apps you opened. The remainder is Idle, the share of the chip doing nothing. A Mac sitting at 90 percent idle is barely working; one at a few percent idle is pinned and will be warm. A healthy Mac at rest spends most of its time mostly idle with brief spikes, while a pegged Mac holds high User or System load steadily, which is the pattern to watch for.

One name worth knowing is kernel_task. If it sits high in the list, leave it alone: that is macOS deliberately taking cycles to hold heat down, so high kernel_task is a symptom of the chip being hot rather than a process gone wrong, and it can't be force quit. Another common high-CPU name is WindowServer, which is the macOS process that draws everything on screen, so it climbs with lots of windows, external displays, or heavy animation; it is normal for it to be busy and not something to quit. If you are wondering what is safe to close, the rule is to quit your own apps and tabs, not unfamiliar system processes.

If you do not want the whole window open, Activity Monitor can put the CPU on its Dock icon. Go to View, then Dock Icon, and choose Show CPU Usage for a live meter or Show CPU History for a rolling graph, and the icon updates in real time so you can glance at it while you work. The CPU History window itself, under the Window menu, draws one live graph per core, which is the clearest way to see how the load is spread and to count how many cores your Mac has.

macOS does not show CPU usage in the menu bar on its own, so a small live percentage up there needs a third-party menu-bar app. That is the same gap that exists for temperature and fan speed, which macOS also keeps hidden. If a constant menu-bar number is what you are after, a third-party tool is the only route, since there is no built-in toggle for it.

If you are comfortable in Terminal, the top command gives you the same live view without opening an app. Open Terminal from Applications, Utilities, type top and press Return, and you get a live text list of processes that refreshes every second or so. To sort it by CPU rather than the default, type top -o cpu instead. Press q to quit back to the prompt when you are done.

This is the keen-user option rather than the everyday one. Activity Monitor shows the same information more clearly with sortable columns and graphs, so reach for top when you are already in Terminal, working on a Mac over SSH, or want a quick check without a window. For most people the CPU tab is the better tool.

Reading the CPU is only half the story, because a busy chip has a consequence you can feel. The harder the CPU works, the more heat it makes, and on a Mac with fans that heat is what spins the fans up. So a process pinned near the top of the % CPU column for a long stretch is usually the same thing making the Mac warm and the fan loud. Once you can read the CPU, you can connect the noise and the heat back to whatever is causing them.

If the high CPU is a stuck process, quitting it fixes the heat and the noise together. But often the load is legitimate, like a video export, a long build, or a heavy call, and the CPU is meant to run high until the work finishes. In that case there is nothing to quit, and the question shifts from the load to the heat it causes. macOS gives you no built-in temperature readout and no fan control, so when the heat climbs you are at the mercy of a fairly cautious fan curve, which is also why a Mac can throttle, the deliberate slowdown explained in what thermal throttling on a Mac is, while the fans are still spinning up. If your fan is loud whenever the CPU is busy, why your Mac fan keeps running covers that side, and for the wider heat picture there is why your Mac gets so hot and how to fix an overheating Mac.

To actually see the heat that high CPU is producing, you need a separate reading, since the CPU percentage and the temperature are two different numbers; the guide on checking your Mac's temperature covers how. And for whether external cooling helps, I have looked at whether cooling pads work for a MacBook honestly. A pegged CPU and a hot, loud Mac that often run together are the reason I built ChillBlades: with Auto Boost, every Auto fan spins up when the hottest sensor reaches a band you pick, then eases off once it falls back below it, so the fans get ahead of the heat the CPU is making instead of trailing it. You can also set a fan to a fixed speed with a slider clamped to that fan's real hardware range, so you can't push it past its rated maximum or stop it dead. It can't cool the chip below what the fans can physically move, and your Mac protects itself regardless, but for a genuinely busy chip, moving more air earlier is the lever. Quit ChillBlades and every fan goes straight back to macOS automatic control.

I make ChillBlades, a Mac fan control app, and I write these guides, so I spend a lot of time watching what the CPU does and what it does to the heat. I have kept this practical rather than promotional: Activity Monitor and the top command are the built-in ways to read CPU usage, and most of the time high CPU is either a runaway process you can quit or legitimate work you should let finish. A fan app does nothing about the load itself; it only helps with the heat that a genuinely busy chip produces, by spinning the fans up earlier. Your Mac protects itself regardless of what any app does. The ChillBlades behavior described here runs on M1 through M5 and Intel Macs with fans, on macOS 13 and later; the base fanless MacBook Air has no fan to control, so it can only throttle to cool down.