In short
- It means apps want more memory than macOS can provide, even after compressing and swapping.
- Save your work, then quit what you don't need. Option, Command and Esc opens Force Quit.
- Activity Monitor's Memory tab shows which app is using the most.
- Judge by memory pressure, not by memory used. Memory cleaner apps don't fix this.
What the message means
Apps have asked for more memory than macOS can give them. When RAM runs short, macOS compresses what it can and moves the rest to files on your disk, called swap. This message appears when that is no longer enough, and macOS asks you to quit something before the Mac stops responding.
Apple describes the parts in its Activity Monitor guide: Swap Used is space on your startup disk, Compressed is memory squeezed to make room, and Wired Memory has to stay in RAM. We found no Apple page that explains this message itself, so the explanation here comes from those definitions.
What to do right now
- Save what you can. If an app still responds, save your work there first. Force quitting loses anything unsaved.
- Quit what you don't need. Press Option, Command and Esc together, select an app in the window that opens, and click Force Quit (Apple's steps). Start with the app you were not using.
- Find what is using the memory. Open Activity Monitor from Applications → Utilities, click Memory, and sort by the Memory column. The graph at the bottom shows memory pressure (what each figure means).
- Restart if it keeps happening. Choose Apple menu → Restart. If the Mac won't respond at all, Apple says to hold the power button for up to 10 seconds until it turns off.
How to read memory pressure
Look at memory pressure, not at how much memory is used. A Mac using nearly all of its RAM can be working normally. Apple says free memory doesn't necessarily mean better performance.
- Green: the Mac is using its RAM efficiently.
- Yellow: it might eventually need more RAM.
- Red: it needs more RAM now. Quit something.
Apple's meanings for each colour are on its page about whether a Mac needs more RAM.
Common causes
- A browser with many tabs. A single heavy tab can take gigabytes, and browsers often run each tab as its own process. In Chrome, choose Window → Task Manager to see which tab it is.
- Video, audio and AI tools. Rendering, voice generation and local AI models hold large amounts of memory while they run, and a loaded model can stay in memory when idle.
- A nearly full disk. Swap lives on your startup disk, so when the disk is nearly full there is less room for it. Free up some space if yours is.
- An app with a leak. If one app keeps growing while you do nothing in it, quit and reopen it, and check for an update.
What doesn't help
"Memory cleaner" apps force macOS to drop what it is holding, and it then has to load the same things back. Quitting the app that is using the memory is what gives it back.
Catching it next time
This message often arrives late, and macOS keeps little record of what led up to a freeze. StorageJanitor, when it is released, has an optional memory watch: it checks every few seconds, warns you when an app grows fast or memory runs low, and shows what was growing before a restart. It never quits anything by itself. You can try the Memory screen in the demo.
Questions people ask
Does this message mean my Mac needs more RAM?
Not necessarily. If it happens once, one app probably used too much. If memory pressure is yellow or red during your normal work, Apple says the Mac might need more RAM. Most current Macs can't be upgraded later, so check before you plan on it.
Will force quitting lose my work?
Anything unsaved in that app can be lost. Save first if the app still responds, and start with apps you weren't using.
Which app should I quit first?
The one using the most that you don't need right now. Activity Monitor's Memory column lists them, and the app you are working in may not be the largest.
Can a full disk cause this message?
It can contribute. Swap is stored on your startup disk, so a nearly full disk leaves less room for it.