A macOS menu bar app with two tools. Thermals shows how hot your Mac's CPU, GPU, memory and SSD are, and runs its fans the way you choose. Power shows where its power goes: what the charger delivers, what the Mac uses, and what goes into or out of the battery, with a history of every charge.
Formerly Pythonflow. Installed copies rename themselves when they update, and keep your history and settings.
A Python rewrite of Powerflow, which crashes on macOS 27 and is no longer maintained.
⬇︎ Download the latest version (free, for Macs with Apple silicon)
- Menu bar reading: the CPU's temperature, the hottest temperature, or system, screen or chip power, or the charger's input while charging. Click it for the fan profiles and a quick summary of temperatures, fans and power.
- Dashboard: the window opens on a short page with a row of readings per tool: CPU, GPU and each fan's speed, with the fan profiles, then system power, battery and charger.
- Temperatures of the CPU and GPU (their hottest core), memory, SSD and ambient air, with a live chart of the last 1, 5 or 15 minutes. In Celsius, or Fahrenheit if you choose it in Settings.
- Fans: each fan's speed, its maximum, and who's in control. Macs without fans show temperatures only.
- Fan control: leave the fans to macOS, or choose a profile that keeps them running and speeds them up sooner (see Fan profiles). You can change Balanced's and Performance's numbers in Settings, and choose which three profiles are in the menu.
- Power flow from charger to Mac to battery, with the charger's conversion loss and where the Mac's power goes.
- Live power chart of the last 1, 5 or 15 minutes.
- Battery and charger details: battery health, cycle count, temperature, voltage and current, and the charger's rating and negotiated voltage.
- Charging history: each charge's levels, duration and power curve, exportable to CSV.
- Works with macOS's charge limit: the time while charging counts to the limit, and Settings has a shortcut to where it's set.
- Starts in the menu bar, at login and when you open it; open it again, or choose Open Dashboard, for the window. Opens at login and keeps itself up to date; both can be turned off in Settings.
- Download
Mac-Engine-Room-….dmgfrom the latest release and open it. - Drag Mac Engine Room into Applications, as the arrow shows.
- Open Mac Engine Room from Applications. Its wattage appears in the menu bar; click it and choose Open Dashboard for the full view.
The first time you open it, macOS may say it can't verify Mac Engine Room. Click Done, then go to System Settings → Privacy & Security, scroll down, and click Open Anyway. You only do this once: Mac Engine Room isn't distributed through Apple, so Apple hasn't checked it. All of its code is in this repository.
The first time you choose a fan profile, macOS asks you to allow Mac Engine Room's fan helper: in System Settings → General → Login Items & Extensions, turn on Mac Engine Room under Allow in the Background and enter your password. Mac Engine Room shows how, and the fans stay with macOS until then.
Tested on macOS 27.0 with Apple silicon. Fan control needs macOS 13 or later. On a desktop Mac, Power shows the whole Mac's power and the chip's, since there's no battery or charger. To build from source, see DEVELOPMENT.md.
- The only connection is the update check: once a day, after your Mac wakes, it asks GitHub for the latest release. It only installs updates signed by the same developer. No analytics, crash reports or web server.
- It reads power and temperature sensors only, never serial numbers or your computer's name. The sensor report in Settings is only made when you click Copy, and only goes where you paste it.
- Fan control uses a small helper that runs as an administrator, because only an administrator can set fan speeds. It's only installed when you choose a fan profile and allow it. All it can do is set fan speeds within each fan's range, give the fans back to macOS, and report on them, and it only answers Mac Engine Room. It gives the fans back to macOS if Mac Engine Room quits or stops responding, and before your Mac sleeps.
- Your data stays on your Mac, in
~/Library/Application Support/Mac Engine Room. You can turn off history recording or delete it in Settings.
| Reading | What it is |
|---|---|
| System | Total power the Mac is using |
| Adapter in | Power from the charger into the Mac. The Adapter box adds the charger's conversion loss. |
| Battery | Power into the battery (positive) or out of it (negative) |
| Screen | Display backlight. On mini-LED screens it rises with bright content. Not shown on a Mac with no screen sensor. |
| Chip (CPU + GPU) | The Apple silicon chip. Apple names the sensor after the heatpipe, but it measures the chip. On a Mac without a working chip sensor, like the 13" M4 MacBook Air, it's the CPU, GPU and Neural Engine from macOS's energy counters instead, which leave out the rest of the chip, so it reads lower. Not shown on a Mac with neither. |
| Time to full / remaining | macOS's own estimate, rough above about 80%, where charging slows down. With a charge limit set, the time to the limit instead, since macOS's estimate counts to 100%. |
| CPU, GPU | The hottest of the chip's per-core sensors. Not its hotspot sensors, which run up to 10° hotter, and not the battery sensors some apps mistake for the GPU. |
| Memory, SSD, Ambient | The hottest sensor in each group. Ambient is the Mac's air temperature sensor. |
A profile runs the fans from the moment you choose it until you choose another. Balanced and Performance keep them at their slowest speed until the hottest CPU or GPU core reaches the profile's start, then speed them up; Max runs them at full speed the whole time. macOS default leaves them to macOS, which stops them when the Mac is cool.
| Profile | Speeds up at | Top speed | Top speed at |
|---|---|---|---|
| macOS default | macOS decides | ||
| Balanced | 55° | 60%, quiet while warm | 70° |
| Performance | 55° | 85% | 65° |
| Max | Always | 100% | Always |
The menu offers three of them, macOS default, Balanced and Max unless you choose others in Settings. All four are on the Dashboard and the Thermals page.
Whatever the profile, the fans go to full speed if macOS reports serious thermal pressure, or the chip, a sensor inside the Mac or the battery gets too hot.
Every Mac model names its sensors a little differently. In Settings, under About, click Copy next to Sensor report, then Report a Problem… and paste it into the issue. It lists your Mac's model, chip and sensors, and nothing that identifies you or your Mac.
Nothing to do: Pythonflow updates itself into Mac Engine Room, renames its app and data folders, and stays open at login if it was. If you install Mac Engine Room by hand instead, opening it quits Pythonflow, moves it to the Trash and takes over its history and settings.
It fixes the original's problems on macOS 27: the crash at launch, blank battery health, "charging" at 100%, "1092 hours" remaining, the menu bar panel that wouldn't open, and the chart freezing after an upgrade.
On first launch it copies over your charging history and preferences, reading the old
database without changing it. You can then delete /Applications/powerflow.app.
Based on Powerflow by The Powerflow Team (Samuel Lyon / lzt1008), under the MIT license; the app icon is Powerflow's. The macOS 27 fixes build on diagnoses from community pull requests #19, #21 and #22.
The per-chip list of CPU and GPU core sensors comes from Stats by Serhiy Mytrovtsiy (MIT), checked against the sensor dumps collected by iSMC by Dinko Korunić.
Fan control is based on ThermalForge by ProducerGuy (MIT): its fan profiles, and the fan and SMC code, which it adapted from macos-smc-fan by Alexander Goodkind (MIT).
Their notices, and those of the libraries the app bundles (Python, pywebview, PyObjC and others), are in THIRD-PARTY-NOTICES, which is also inside the app.
Copyright (C) 2026 DigitalN
Mac Engine Room is free software, licensed under the GNU General Public License, version 3 or (at your option) any later version. See LICENSE. Releases up to 1.2.17 were MIT-licensed.