Why is my Mac so hot? How to find what's heating it
A hot Mac is almost always a busy Mac. Something is keeping the processor working: an app you can see, or a process you didn't know was running. Find it, and you've found the heat.
The short answer: open Activity Monitor, click the CPU tab, then click the % CPU column so the busiest process is at the top. Anything above about 80% for more than a minute or two is your likely culprit.
1. Find the busiest process
With Activity Monitor
- Open Activity Monitor (press ⌘ Space and type "Activity Monitor").
- Click the CPU tab and sort by % CPU.
- Then click the Energy tab and sort by Energy Impact. This is closer to what makes heat, because it counts the graphics chip and how often an app wakes the processor, not just raw CPU time.
A single process can show more than 100%: that means it's using more than one core.
With Terminal
This lists the eight busiest processes. The first of top's two samples is always empty, so it takes two and shows the second:
top -l 2 -o cpu -n 8 -stats pid,command,cpu,power | tail -9The POWER column is the same energy number Activity Monitor shows. For the most detail, including whether macOS has started slowing the processor to cool it, run:
sudo powermetrics --samplers tasks,thermal --show-process-energy -n 1 -i 5000It needs your password, takes one five-second sample, and lists every process with its energy, plus the Mac's current thermal pressure.
2. Know the usual suspects
Some names you'll see near the top, and what they mean:
- kernel_task: not the cause. When your Mac gets hot, macOS gives kernel_task processor time on purpose, so other apps get less and the chip can cool. If it's high, look at what's below it.
- WindowServer: draws everything on screen. It runs hot with external displays, lots of open windows, or an app that animates constantly.
- mds_stores, mdworker: Spotlight indexing. Normal for an hour or so after a macOS update or copying in lots of files. It stops on its own.
- photoanalysisd: Photos scanning your library for faces and objects. It works while you're away and usually finishes in a day or two.
- qemu-system-aarch64: the Android emulator. It keeps a whole phone running, even when its window is hidden.
- com.apple.Virtualization.VirtualMachine, OrbStack Helper, Docker: a Linux VM for containers. It keeps working while containers run in the background.
- node, ruby, python, java: usually a dev server, a watcher or a build you started in Terminal and forgot.
- Browser Helper (Renderer): one browser tab. Find which in the browser's own task manager: in Chrome it's Window › Task Manager.
3. Cool it down
Quit it. If it's an app you don't need right now, quit it normally. For a process started in Terminal, press Control-C in its window, or stop it by its process ID from the list above:
kill 4821Only stop processes you recognise. Leave anything owned by macOS (most names starting with com.apple. or ending in d) alone: it will restart, and some are doing work you need.
Slow it down instead. If you need it to keep running, you can move it to the Mac's background band. It keeps working on the efficiency cores at low priority: slower, but much cooler.
taskpolicy -b -p 4821Undo it with taskpolicy -B -p 4821. It only works for your own processes, and it lasts until the process quits.
Check the basics. A Mac on a bed or a lap can't breathe: the vents on most MacBooks are along the back edge and underneath. And direct sun on a laptop heats it faster than any app.
The faster way
Steamie does all of this from your menu bar. It shows how many watts your Mac is using right now and which app is behind it, names the confusing processes in plain words (that qemu-system-aarch64 is the Android emulator from your trailmix project), and lets you quit or calm an app in one click. Calm is the same background band as taskpolicy -b.