MacBook overheating and the fan is loud: what is making the heat, and what to do

Heat is caused by work, and the fan is the cure

Every bit of computing a Mac does turns electricity into heat. A chip running flat out produces tens of watts of it, and the only place that heat can go is into the aluminum case and, on models that have one, out through the fan. So a hot MacBook and a loud fan are not two problems. They are one fact (something is working hard) and one correct response (the Mac is cooling itself). The fan at full speed sounds alarming, but a fan that did not spin up under load would be the fault.

That reframes the question. Instead of "how do I stop the fan", ask "what is working hard, and is it something I asked for?" Most of the time it is: a video call, a 4K export, a game. The fan noise ends when the work ends. Some of the time it is work you did not ask for and did not know about: a background indexer, a stuck process, a web page running a script in a loop. That is the case worth diagnosing, and Activity Monitor shows it in ten seconds.

There is one more category: the Mac is working normally but cannot shed the heat, because its vents are covered, blocked with dust, or it is sitting on a duvet. Then the chip slows itself down to stay safe, everything feels sluggish, and a process called kernel_task appears at the top of Activity Monitor. That is covered below, because it confuses almost everyone.

What usually makes a MacBook hot

The chart ranks the common heat sources by how hard they typically push the CPU and GPU. The numbers are typical ranges you will see in Activity Monitor's % CPU column (where 100% is one core, so a busy 8-core chip can show 800%), not lab measurements, but they match what people report in the threads linked at the bottom of this page.

A few notes on the ones people miss. Video calls are the single most common "my Mac is overheating" complaint and the most innocent: the Mac is encoding a camera feed and decoding several others at once, which is sustained work for an hour. Turning off background blur and video effects, or closing the preview of your own camera, takes a visible chunk off. Browser tabs are the sneakiest, because the browser's own CPU number is spread across helper processes; our page on finding the tab that is eating resources shows how to pin it down in Chrome, Safari and Firefox. Indexing is the one that strikes a day after a macOS update, when you have forgotten the update happened: mds_stores for Spotlight, photoanalysisd and mediaanalysisd for Photos. Both pause when you are on battery and resume when you plug in, which is why the fan starts the moment you connect the charger. External displays push WindowServer hard when the display runs at a "looks like" scaled resolution; picking the native or a default resolution in System Settings, Displays can cut that in half.

Why kernel_task is at the top, and why it is not the problem

Open Activity Monitor on a hot Mac and the top process is often kernel_task, sometimes at several hundred percent CPU. It looks like the culprit. It is the opposite. kernel_task is macOS itself, and one of its jobs is thermal management: when the chip's temperature sensors get close to the limit, the kernel deliberately occupies CPU time with nothing, so that other processes get less of it and the chip cools. The high number is the Mac reducing its own heat output. Howard Oakley's write-up, linked in the sources, puts it in one sentence: kernel_task isn't causing the thermal problem, it's part of your Mac's response to it.

So when kernel_task is high, the real question is why the Mac got hot enough to trigger it. Usually one of two things. Something else is or was running hard (look at the next few lines in Activity Monitor, or the processes that were busy a minute ago). Or heat cannot escape: the Mac is on a bed or sofa, the vents along the hinge are blocked, there is a layer of dust inside after a few years, or a charger and a hot external drive are sitting against the case. On Intel MacBooks with a Thunderbolt port on each side, charging through the left-hand ports has been known to heat the sensor near them and trigger kernel_task; moving the charger to the right side fixes it, oddly but reliably.

You cannot quit kernel_task, and you would not want to. Fix the heat and it falls on its own within a minute. If kernel_task stays high on a Mac that is cool to the touch, with nothing else running, after a restart, that points at a faulty temperature sensor or a disconnected fan, which is a hardware repair. Apple Diagnostics (hold the power button at startup on Apple silicon and choose Options, or hold D on Intel) reports fan and sensor faults as PPF and PPT codes.

What temperatures are normal for a MacBook

Apple silicon chips (M1 through the current generation) are designed to run up to about 100 C at the die under sustained load, and they manage themselves to stay just under that line. A CPU reading of 90 to 100 C during an export or a game is the chip working as intended, not a warning. Intel MacBooks behave the same way at a similar ceiling. The case cannot reach those temperatures; by the time heat spreads through the aluminum, the surface above the chip is typically 40 to 50 C, which is uncomfortably warm on your lap but far from dangerous to the machine. Idle, with nothing open, an Apple silicon Mac sits around 30 to 40 C at the chip and the fan (if it has one) is off.

Three things are worth knowing. The MacBook Air has no fan at all, from the M1 onward; it cools entirely through the case, which is why it gets warmer to the touch than a Pro and why it throttles sooner under long loads. That is by design, and it is why Air owners search "overheating" more than Pro owners while nothing is wrong. The MacBook Pro's fans are nearly silent under light and medium load and only become audible past roughly 3,000 rpm, so hearing the fan means sustained heavy work, not a fault. And throttling is normal: when the chip reaches its limit it drops its clock speed to hold the temperature, and performance dips slightly rather than the machine shutting down. A Mac only powers itself off from heat when a sensor reports something far outside its range, which almost always means a hardware fault or a blocked fan, not a hot room.

If you want to watch the numbers, macOS does not show chip temperature anywhere in its own interface. The Mac temperature monitor guide covers the safe ways to read it, and Safe to Quit shows the thermal pressure level alongside the process that is causing it in the menu bar, which is the pairing that actually answers the question.

What is your Mac doing with that heat?

Pick what you have been doing in the last half hour and the widget shows where the heat is most likely coming from and whether it will stop on its own.

Most answers end in "wait" or "close the thing you opened". The ones that end in "check Activity Monitor" are the cases where a process you did not start is running, and the next section is the way to find it.

What to do, in order, when a MacBook is overheating

Safest first. Most hot Macs are fixed at step two or three, and none of these steps can make anything worse.

1. Move it to a hard, flat surface

   Lift it off the bed, sofa, lap or paper pile. The vents on a MacBook Pro run along the hinge and the sides; a MacBook Air sheds heat through its whole underside. Give it air for two minutes and see whether the fan slows.

2. Open Activity Monitor and sort by % CPU

   Spotlight, type Activity Monitor, press Return. Click the CPU tab, then the % CPU column header until the arrow points down. Read the top three lines. If it is an app you are using (Zoom, Chrome, Final Cut), that is your heat and it is expected. If it is a name you do not recognize, look it up before doing anything.

3. Close what you are not using

   Quit apps rather than closing windows (Command + Q, not the red button). Close browser tabs with video, live feeds or games in them. End the video call's camera preview or turn off background effects. On Apple silicon this alone drops most Macs out of fan territory within a minute.

4. Let indexing finish if that is what it is

   If mds_stores, mdworker, photoanalysisd or mediaanalysisd are at the top and you updated macOS or imported a lot of files recently, the Mac is building indexes. Leave it plugged in and awake, ideally overnight. It finishes on its own and does not come back.

5. Check the external display setting

   If WindowServer is high and you use an external monitor, open System Settings, Displays, select the external display and pick Default for display or the native resolution instead of a scaled one. Disconnect the display briefly to confirm it is the cause.

6. Try Low Power Mode

   System Settings, Battery, Energy Mode (or Low Power Mode on older versions). It caps the chip's peak speed, which cuts heat and fan noise with a small, usually invisible, cost in performance. Good for long video calls on a hot day.

7. Restart

   If a process stays at 100% CPU for hours with nothing visible happening, or kernel_task stays high after everything else is quiet, restart. It clears stuck processes and resets the thermal state. If the same process returns within minutes, the page for that process explains what it is waiting for.

8. Clean the vents or get the fan checked

   A Mac that is a few years old and now runs hot doing the same work it used to do cool usually has dust in the fan and heatsink. Compressed air through the hinge vents helps a little; a proper clean by a repair shop helps a lot. Run Apple Diagnostics if the fan is silent even under heavy load.

What not to do: SMC resets, fan apps and cleaners

Searching "MacBook overheating" produces a lot of confident advice from the Intel era that no longer applies, and some that never did.

• Resetting the SMC. On Intel Macs the System Management Controller handles fans and power, and resetting it (a key combination at startup) occasionally fixed a fan stuck at full speed. Apple silicon Macs have no SMC to reset; the equivalent is simply shutting down, waiting 30 seconds and starting up. Any guide telling you to hold Shift + Control + Option on an M-series MacBook is describing a step that does nothing.
• Fan control apps. Tools that let you set fan speed by hand can make a hot Mac quieter by lowering the fan, which makes it hotter, or louder by raising it, which makes it cooler than it needs to be and wears the fan. macOS already runs the fan from the sensors with a curve Apple tuned for each model. The one legitimate use is forcing fans to maximum briefly to confirm they spin. Otherwise, leave it.
• Cleaner and optimizer apps. Heat comes from work. A cleaner that deletes caches and "frees memory" does not reduce work; often it creates some, because the Mac has to rebuild what was deleted. See whether a Mac cleaner is worth it for the longer version.
• Cooling pads. Mostly harmless and mostly pointless on a MacBook, whose vents are at the hinge rather than underneath. A hard surface with the back edge slightly raised does as much.
• Force quitting system processes. kernel_task, WindowServer, mds_stores and the rest either cannot be quit or restart themselves immediately and begin their work again from scratch, which is more heat, not less.
• Reinstalling macOS or a factory reset. A heat problem that survives a restart is either a specific app or extension, or dust. A reinstall fixes neither and costs an evening.

When to worry about a hot MacBook

Heat is a worry in only a few specific situations.

• The Mac shuts itself off. Not a crash or a restart, but a thermal shutdown with no warning, more than once. That means a sensor is reading far outside normal, or the fan has failed. Run Apple Diagnostics and get it looked at.
• It is hot and loud while doing nothing. Nothing in Activity Monitor above 10% CPU, no indexing in progress, cool room, and the fan is still at full speed an hour after a restart. That is a sensor or fan fault, or a kernel extension misbehaving. Boot into safe mode (hold Shift at startup on Intel; hold the power button and choose the volume, then Shift, on Apple silicon) and see whether it is calm; if so, a third-party extension or login item is the cause.
• The battery is swelling. A trackpad that no longer clicks properly or a bottom case that no longer sits flat is a swollen battery, which is a safety issue. Stop using it and book a repair.
• A specific process is at 100% for days. Not indexing (which finishes) but a stuck helper that never completes. Quitting it is safe if it is a user process; the process pages on this site say which ones are.

Everything else, which is nearly all of it, is a Mac doing what you asked, loudly. Close the tab, finish the export, let the index build overnight, and it goes quiet.