Check your Mac's CPU temperature, fan speed, GPU and Neural Engine

Where to find temperatures and fans

Open Mac Health and choose the Heat tab. It has four cards: Temperatures, Fans, Graphics and Neural Engine and Working hardest. The Temperature and GPU tiles at the top of Mac Health show the short version all the time, whichever tab you're on.

Temperatures are shown in your region's unit unless you choose otherwise under Settings › Appearance › Temperatures in: Your region's unit, Celsius (°C) or Fahrenheit (°F). The setting applies everywhere: the tile, this tab, History's chart, the menu bar and alerts' messages.

For the wider picture of what's slowing your Mac (memory, disk and CPU as well as heat), see the Mac Health overview.

Is my Mac too hot? What the thermal state means

The first line of the Temperatures card is the one that matters. It isn't Mac Health's opinion: it's macOS's own judgement of whether it has to slow the Mac down to keep it cool. There are four states:

When the state is Hot or Very hot, the Temperature check at the top of Mac Health turns orange or red, and the headline becomes “Running hot”, naming the hottest part and the app using the most CPU, for example “Running hot: CPU 96 °C, Xcode is using 6 cores”.

A busy kernel_task in the Apps tab is often a sign of heat rather than a problem in itself: it's the core of macOS, and it uses CPU time on purpose to hold other work back when the Mac is too hot.

Which temperature sensors Mac Health reads

Below the thermal state, the card shows up to five figures in °C or °F:

Which sensors a Mac has differs by chip. The first time Mac Health runs on a Mac, it finds that Mac's sensors once and remembers the list for that model and version of macOS, then reads only those. Sensors that report nonsense (a sensor that isn't fitted can read 0 or 7 °C) are ignored. If none can be read, the card says “This Mac's temperature sensors couldn't be read.”

The Temperature tile at the top also tells you which part is hottest overall, for example “hottest: CPU 74 °C”, comparing the CPU's hottest sensor, the GPU, the SSD and the battery.

How to check Mac fan speed

The Fans card lists each fan as Fan (when there's only one) or Fan 1, Fan 2 and so on, with its speed in rpm. When the Mac reports a fan's minimum and maximum speeds, a bar shows how fast it's spinning between the two; the bar turns red above 80% of its range. A MacBook Pro working hard might show two fans at around 2,400 rpm with bars well under half.

Fan speeds are read only. As the card says, “OneMacTools never changes fan speeds, which macOS manages better.” If you want the fans quieter, reduce the work: the Working hardest card at the bottom of the tab lists the five apps using the most CPU (at least 5% of a core), each with a quit menu.

Macs without fans

A MacBook Air has no fans. On these Macs the card says “No fans: this Mac cools passively, so it slows itself down a little when hot instead.” That's why the thermal state at the top of the tab is the better guide on a fanless Mac: it tells you when that slowing down has started. If a Mac does have fans but doesn't report them, you'll see “Fan speeds aren't available on this Mac.”

GPU and Neural Engine use

The Graphics and Neural Engine card shows:

• GPU: how busy the graphics chip is, as a percentage.
• Neural Engine: In use or Idle. The Neural Engine runs on-device AI such as dictation, Live Text, photo search and local models. macOS shows whether it's working, not how hard or for which app, so Mac Health can't break it down further.
• The apps using the GPU most right now (those at 1% or more), with their share.

When on-device AI is working, including OneMacTools' own on-device AI features, this is where you'll see the Neural Engine switch to In use, and the GPU tile at the top reads “Neural Engine in use”.

Power in watts for each chip

With the optional admin helper installed (Settings › Admin Helper), the card adds CPU power, GPU power, Neural Engine power and Memory power in watts. Some versions of macOS keep the CPU, Neural Engine and memory counters still even with admin rights; then only the GPU's power is shown, and the card explains why. Without the helper it says that power in watts needs the admin helper.

Temperature over time, alerts and the menu bar

The Heat tab shows the present. For the past, open Mac Health › History: when temperatures have been recorded you'll find a CPU temperature chart, and when the GPU or Neural Engine has been used, GPU and Neural Engine in use (as a percentage of the time) charts too. Click any point to see which apps were busiest then. See performance history and alerts.

Heat alerts come in two kinds:

• The Mac stays hot for 5 minutes is built in and on by default. It fires when macOS's thermal state stays at Hot or above, and names the app working hardest.
• You can add your own in Settings › Alerts › Add Alert…: choose The Mac, then CPU temperature (in °C), GPU (in %) or Heat (1 warm, 2 hot, 3 very hot), a value and how many minutes it must last.

To keep an eye on heat without opening anything, add the Temperature readout to the menu bar. It shows the CPU temperature as a short figure such as “61°”, with a small graph drawn between 30 °C and 110 °C, and turns red when the Mac is hot enough to slow down. The menu bar dropdown also shows the hottest part. See the menu bar system monitor.

What to do when your Mac runs hot

Mac Health tells you what's causing the heat. Here's how to use it:

1. Look at the first line of the Temperatures card. If it says Normal or Warm, nothing is being slowed down and there's nothing to fix.
2. If it says Hot or Very hot, check Working hardest at the bottom of the tab, or sort the Apps tab by CPU.
3. Quit or pause what you don't need right now. A runaway browser tab shows up in Chrome's expanded row under Tabs.
4. If heat comes from the GPU (games, video exports, local AI models), the GPU list in Graphics and Neural Engine names the app.
5. If heat keeps coming back at the same time of day, open History, choose 7 days and click the spikes in the CPU temperature chart to see which apps were behind them.

For a long video export or a build, press Record before you start. Mac Health then reads the Mac every second, including temperature and GPU, and shows you the peak and the app behind it when you stop.

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