Gauge: free Mac system monitor
Gauge is a small, free Mac app from the Rig team that sits in your menu bar and tells you how your Mac is doing: how hard the processor is working, how warm the chip is, whether memory is under pressure, how fast the fans are spinning, whether Time Machine is keeping up, and why the Mac restarted last time. It is separate from Rig. You do not need Rig, or a Rig account, to use it. This guide covers installing Gauge, what each part of it shows, the optional fan helper, and the questions people ask most.
Rig and Gauge are different jobs
Rig runs and watches your development projects: dev servers, databases, workers and the logs they print. Gauge watches the Mac itself. It does not start, stop or restart your projects. If Gauge shows a dev server eating memory, it points you back to Rig to stop it properly, so the project’s state stays correct. Many developers run both, side by side in the menu bar.
Free, with no account
Gauge is free, with no trial, no paid version and no account. It does not ask you to sign in and it does not need an internet connection to work, apart from checking for updates.
Install
- Check your Mac runs macOS 13 Ventura or later. Gauge works on Apple silicon and Intel Macs.
- Open userig.app/download/gauge and pick the build for your Mac: Apple silicon for M series Macs, Intel for older ones. If you are not sure, open the Apple menu → About This Mac and look at Chip or Processor.
- Open the downloaded file and drag Gauge into Applications.
- Open Gauge from Applications. Its icon appears in the menu bar, near the clock.
The first time it opens, Gauge walks you through two short steps. The first is choosing what sits next to the clock. The second is fan control, which is optional and can be skipped; every other part of Gauge works without it.
What sits next to the clock
You choose what the menu bar item shows: just the icon, the processor load, the temperature, or processor load and temperature together. Click it to open a small panel with the main numbers. Open the full Gauge window from there for the details below.
Overview
The Overview shows processor load, chip temperature, memory, fans and power at a glance, with history for the last hour, the last 24 hours or the last 7 days. History is useful for questions like “was the Mac hot all afternoon, or only during that build?”. On Apple silicon, total power and processor power are live, but the graphics power figure stays blank, because macOS does not report it on those chips.
Memory, and why Gauge talks about swap
macOS uses as much memory as it can on purpose, so “memory nearly full” on its own is not a problem. The real sign of memory pressure is swap: the Mac moving memory out to disk because it ran out of room. Gauge shows memory that is using swap, and treats swap falling to zero as the check that pressure is off. It deliberately does not show a “GB freed” number, because that number would not mean much.
Processes
The Processes view lists what is using your Mac, grouped by app. All the helper processes that Chrome, Docker or other apps start are folded into one row each, so you see “Chrome” rather than forty entries. Gauge also keeps a list of this week’s Jetsam guests: the apps macOS had to close because memory was tight.
With one confirm, Quit this week’s hogs asks those apps to quit. Some processes are protected and have no quit button at all. WindowServer, which draws your screen, is never quit, and Gauge’s own fan helper is managed from Settings instead. If a hog is one of your dev servers, Gauge suggests stopping it in Rig instead. After a quit, watch swap: when it falls to zero, memory pressure is off.
Restarts and crashes
When a Mac restarts by itself, it is hard to know why. Gauge reads the reports macOS leaves behind and sorts each restart into plain categories:
- Kernel panic. The core of macOS crashed. That is a true panic, not an app crash.
- Watchdog. A system service stopped answering and macOS restarted it. That can look like the Mac rebooted itself.
- Jetsam. macOS closed processes because memory was tight. On its own that is not a full restart.
- No report. Power loss, a held power button, a brownout or a normal restart all leave no report, so Gauge says so plainly.
Each entry says what it means and what to try. The Crashes list shows apps that crashed while macOS kept running.
Logs and Full Disk Access
Everything in Gauge works without any special permission, except reading the full set of crash and diagnostic reports. If Logs says Full Disk Access is off, choose the button to open Privacy and Security in System Settings, turn Full Disk Access on for Gauge, and reopen it. You can leave it off if you prefer; you will just see fewer reports.
Fans and the fan helper
Reading fan speeds needs nothing extra. Changing them needs a small helper that Gauge installs with your permission. macOS asks for your password once to install it, and Gauge never stores your password. In Auto mode macOS sets the fans and the sliders show what it chose. In manual mode you can set each fan, or move both together.
- Gauge never lets a fan go below its hardware minimum.
- Manual control is never sticky. It ends when you quit Gauge, when the Mac sleeps, or when it restarts, and the fans go back to macOS.
- If Gauge loses contact with the helper, it hands the fans back to macOS straight away.
- If Settings → Fan helper says the helper is behind, choose Update helper. You can also remove it there; manual control stops immediately and reading fan speeds still works.
Notifications
Turn on “Tell me when things aren’t going to plan” in Settings and Gauge sends a notification when:
- the chip goes over 95°C or is slowing itself down to stay cool;
- Time Machine has not backed up for 48 hours, or its last attempt failed;
- the Mac had a watchdog restart, a kernel panic, or a restart with no crash report.
Settings
- How often Gauge reads: every 1, 2 or 5 seconds. Slower uses a little less power.
- Light, dark, or match the Mac.
- Open Gauge when you log in.
- What sits next to the clock.
Updates
Gauge updates itself. When a new version is out it offers to install it, the same way Rig for Mac does. You can also download the latest build from the Gauge download page and drag it over the old one.
Uninstall
- If you installed the fan helper, remove it first from Settings → Fan helper.
- Quit Gauge from its menu bar panel.
- Move Gauge from Applications to the Trash.