Temperature alone can mislead you. One Mac is fine at a temperature that would already have another one cutting back, so the number on a sensor doesn't tell you whether you're losing speed. Below are the checks you can run yourself, what each one shows on Apple silicon and Intel, and a simpler way to keep an eye on it.

#What thermal throttling is

When a Mac gets too hot, macOS lowers how hard the processor works so it makes less heat. Fans, if your Mac has them, spin up first. If that isn't enough, performance drops. It happens without a message, so all you notice is that an export, a build or a game suddenly feels slow.

macOS tracks this as a pressure level. The levels are Nominal, Moderate, Heavy, Trapping and Sleeping. Nominal is normal. Moderate means the Mac is warming up. Heavy is where throttling begins. The last two are rare and extreme.

#Way 1: pmset -g therm

pmset is built into macOS and doesn't need an administrator password. Its man page says -g therm "shows thermal conditions that affect CPU speed" and that it is "not available on all platforms".

pmset -g therm

On an Apple silicon Mac running macOS 26 Tahoe, the result looks like this:

Note: No thermal warning level has been recorded
Note: No performance warning level has been recorded
Note: No CPU power status has been recorded

On Intel Macs, this command can report values such as CPU_Speed_Limit, a percentage where anything below 100 means macOS has capped the processor's speed.

#What this way can't do

On Apple silicon, these notes are not much to go on. Stanislas Lange, who wrote the open-source MacThrottle, found that pmset's thermal log showed only "No ... has been recorded" notes while he stress-tested an Apple silicon Mac. So a clean result there isn't proof that all is well. Treat pmset -g therm as a useful check on Intel and a weak one on Apple silicon.

#Way 2: powermetrics (needs sudo)

powermetrics is Apple's built-in tool for CPU, GPU and power statistics, and it has a sampler just for thermal pressure. Its man page describes the thermal sampler as showing "the current thermal pressure the system is under". It needs administrator rights, so it runs with sudo and asks for your password.

To take one reading:

sudo powermetrics --samplers thermal -n 1

The output includes a line like:

Current pressure level: Nominal

To watch it change while you run something heavy, take a reading every second and press Control-C to stop:

sudo powermetrics --samplers thermal -i 1000

If the level moves from Nominal to Moderate, your Mac is getting warm. If it reaches Heavy, it is throttling.

The cpu_power sampler shows CPU power and frequency information, which lets you see the drop for yourself: during throttling, the CPU can stay busy while its power and frequency fall.

sudo powermetrics --samplers thermal,cpu_power -i 1000

#Apple silicon vs Intel

The samplers differ by Mac. Run powermetrics -h (no sudo needed) to see the list your Mac supports. On Apple silicon it includes thermal, cpu_power, gpu_power and ane_power. The man page also describes an smc sampler with fan speed and temperature sensors "on supported platforms", but it isn't in the list on an Apple silicon Mac.

powermetrics -h

The man page has more detail:

man powermetrics

#What this way can't do

It's a Terminal window you have to keep open, it needs your password, and the man page notes each reading is an instantaneous value taken at the end of the sample window. It's good for testing a hunch, not for noticing throttling during an ordinary afternoon.

#Way 3: Activity Monitor

Activity Monitor can't show the pressure level, but it helps you find the cause. Apple's guide to keeping your Mac laptop within acceptable operating temperatures suggests it when a Mac stays warm without heavy work, or its fans run for a long time.

1. Open Activity Monitor (in Applications > Utilities).
2. Click CPU.
3. Sort by % CPU to see what is working hardest. Look for something you didn't expect, like a stuck browser tab or a background process running flat out.
4. Choose Window > CPU History to see recent activity over time.

At the bottom of the window, Apple's Activity Monitor guide explains the split: System is macOS, User is your apps, and Idle is unused capacity.

The telltale pattern is high CPU use while the work takes longer than usual. That points to heat as the limit, but Activity Monitor can't confirm it on its own.

#Before you blame heat: Low Power Mode

A Mac in Low Power Mode is slower on purpose, and that isn't throttling. Apple's article About Power Modes on your Mac says Low Power Mode "reduces energy use to increase battery life", and on supported models it also lowers fan noise.

To check it:

1. Choose Apple menu > System Settings.
2. Click Battery (on a desktop Mac, Energy).
3. Look at Energy Mode for "On battery" and "On power adapter".

Some MacBook Pro, Mac mini and Mac Studio models also have High Power Mode, which lets the fans run faster in very intensive work. Apple's article lists which models have each mode.

Simple habits help too. Apple's fans and fan noise article recommends using the Mac on a hard, flat surface with the vents clear, and Apple suggests an ambient temperature between 10° and 35° C (50° and 95° F) for Mac laptops.

#The simpler way: MyMacIsHot

MyMacIsHot is a small menu bar app that keeps watching the same pressure level, so you don't have to run Terminal commands. It puts a face in the menu bar: calm and monochrome while all is well, and in colour when heat starts to matter.

It reads the five-level thermal pressure without an admin password, a helper or a background service. It reports Moderate and Heavy separately, which matters because Heavy is where throttling begins, and it groups the two rare extreme levels as Critical. Click the face for the hottest CPU or GPU core temperature, fan speed in RPM, a ten-minute graph and how long your Mac has spent throttled. Optional notifications tell you once when throttling starts, turns critical or clears.

It runs on macOS 15 Sequoia or later, on Apple silicon and Intel, and costs $4.99 once. It's a monitor, not a hardware diagnostic: if you suspect a fault, contact Apple.

#FAQ

#Is my Mac throttling if it feels hot?

Not necessarily. Macs run warm under load and turn their fans up first. Throttling starts when the thermal pressure level reaches Heavy, which you can check with sudo powermetrics --samplers thermal.

#Why does pmset -g therm say nothing has been recorded?

On Apple silicon Macs, that is the usual result, and it has been reported even during stress tests. Use powermetrics with the thermal sampler for a clearer answer. On Intel Macs, look for a CPU_Speed_Limit below 100.

#Can I check thermal pressure without sudo?

The built-in tool that prints the pressure level, powermetrics, needs sudo. Menu bar apps such as MyMacIsHot read the same level without an admin password.

#Does Low Power Mode cause throttling?

Low Power Mode lowers energy use on purpose, so your Mac may be slower, but that's a setting you chose, not heat. Check System Settings > Battery (or Energy) to see which mode is on.

#Do Apple silicon Macs throttle?

Yes. Under long, heavy work they can reach Heavy thermal pressure and slow down, like any Mac. The pressure level is the same signal on Apple silicon and Intel.