Fan speed and fan curves for Apple Silicon
macOS keeps the fans quiet until the chip is already hot. Stat Space shows every fan’s RPM next to the temperatures, and if you turn it on, lets you set a speed by hand or draw a curve that ramps the fans up earlier.
Live readout
Every fan’s current RPM next to CPU and GPU temperatures and power in watts, in the System tab or as a tile pinned to Home.
Manual speed
Pin a fan to a fixed speed for a render or a long build, anywhere between its minimum and maximum RPM.
Temperature curve
Set a temperature and a fan speed for each point of a curve, following the CPU, the GPU or whichever is hottest, with a live preview. Reset to the default curve any time.
No fan hunting
Temperatures have to fall 3 °C below the last decision before the fans slow down, so they don’t rev up and down every few seconds.
Opt-in helper
Writing fan speeds needs root, so control uses a small helper installed only when you turn it on and removed when you turn it off.
Safe on exit
When the helper stops, for whatever reason, every fan goes back to automatic control.
Readout first, control if you want it
Fan speeds are read from the SMC through IOKit with no helper and no permission, so the readout is on for everyone. Control is a separate switch in Settings › Fans. Turning it on registers a launch daemon through macOS’s SMAppService; macOS asks you to approve it in System Settings › General › Login Items. That daemon is the only root component in Stat Space, and it doesn’t exist until you ask for it.
Why a curve beats a fixed speed
A fixed 5,000 rpm is loud while you read email and still might not be enough during a compile. A curve scales with the work: quiet at idle, ramping from, say, 60 °C, and full speed near the top. Pick the CPU, the GPU or the hottest of both as the source. The 3 °C hysteresis stops the fan from oscillating when the temperature sits right on a curve point.
When to use it
Sustained loads are where a curve pays off: long Xcode or Rust builds, video exports, local LLMs and games on a MacBook Pro or Mac Studio. Apple’s default control lets the chip run hot before the fans ramp, which is fine for longevity but can mean lower sustained clocks. For bursty everyday work, leaving fan control off is perfectly reasonable.
What it doesn’t do
It doesn’t override macOS’s thermal protection, and it can’t make a fan spin slower than its minimum. Apple’s automatic control comes back the moment you disable fan control or quit the helper. If you want profiles per app or a full fan control suite, a dedicated tool may fit better; see the fan control apps roundup.
Questions
Does it work on a MacBook Air?
MacBook Airs with Apple Silicon have no fan, so there’s nothing to control. Stat Space still shows their temperatures, power and thermal state.
Can I turn the fans off or below the minimum?
No. Speeds are always kept between the fan’s own minimum and maximum RPM as reported by the Mac, so you can make it louder earlier but not quieter than Apple allows.
Is a root helper safe?
The helper only accepts connections from the Stat Space app signed by its own developer team, checked by the system before any message arrives. It does one job: writing fan targets to the SMC. You approve it in System Settings, and turning fan control off removes it.
Will faster fans stop thermal throttling?
Sometimes. Running the fans harder earlier keeps the chip cooler under sustained load, which can delay throttling. It won’t make a passively limited chip faster, and it’s louder.
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