64 gb of ram, and it says it is out of memory

which kind of out of application memory you have

check swap usage in one command

open Terminal and run sysctl vm.swapusage. no password, nothing to install, about a second:

vm.swapusage: total = 9216.00M used = 8482.56M free = 733.44M (encrypted)

total is how much swap macOS has set up so far, used is how much of it holds real data, and free is what is left inside the space already reserved — not what is left on the disk. that distinction is why the dialog surprises people: free can read a few hundred megabytes while the volume still has room, because macOS simply sets up more swap when it wants more.

where the swap file is

ls -lh /System/Volumes/VM/ lists them. on the Mac those numbers came from there are nine, swapfile0 through swapfile8, each exactly 1.0G — nine gigabytes, which is what total said. that is how swap grows: whole gigabyte files, one at a time, each carrying the date it appeared. those dates mark the days that pushed the machine hardest.

what memory_pressure will not tell you

there is a command for this too — /usr/bin/memory_pressure — and it runs without sudo. pages that send you looking for a pressure level never mention what it will not give you, so: it does not print green, amber or red. it prints raw counters — pages free, pages compressed, swapins and swapouts — and one line, «System-wide memory free percentage». the coloured indicator exists in Activity Monitor's window and nowhere else.

the colour is a summary of how hard macOS is working to keep everything supplied, not a fullness gauge, and it measures something narrower than most pages assume: what memory pressure actually measures

what Activity Monitor adds on top

1. open Activity Monitor — ⌘Space, type the name — and go to the Memory tab.
2. look at the bottom: Memory Pressure, and next to it Swap Used.
3. then check free disk space: Apple menu → System Settings → General → Storage.

Apple defines the field as «the amount of space being used on your startup disk to swap unused files to and from RAM», and its page does not mention the colours either: view memory usage in Activity Monitor — Apple Support

• swap used is large and the disk is nearly full → this is a disk problem. free space and the message stops; adding ram would not have helped.
• memory pressure is red and swap is modest → genuinely out of ram, right now, for what you are doing.
• pressure is green and one process holds an absurd amount → that process is leaking, and quitting it is the whole fix.

the third case is behind most of these dialogs on healthy Macs, and it is why «restart and it went away» is such common and useless advice: restarting kills the leak, teaches you nothing, and it comes back on Thursday.

how much free disk space macOS needs for swap

the number everyone quotes is not a number Apple published. there is no documented minimum free space for swap anywhere — not in the Activity Monitor guide, not in the virtual memory explanation, not on the storage page. the figures in circulation each came from somewhere else:

• «ten percent of the disk» — travels through the pages of utility vendors, with nothing behind it.
• «fifty to a hundred gigabytes» — a reply from another user in an Apple Community thread, repeated since as if Apple had said it.
• «as much free space as you have ram» — folklore, and it does not survive contact with a 64 gb machine.

none of the three can be checked against sysctl, and none appears on support.apple.com. what the system does has no threshold in it: it asks for another gigabyte file when it wants one and keeps getting them until the volume refuses. there is no line it crosses and warns you about, which is why the dialog arrives without warning.

what to watch instead of a percentage

• run sysctl vm.swapusage twice, an hour apart. used climbing while you are doing the same work is the signal.
• count the files in /System/Volumes/VM/. one dated today means macOS reached for more room today.
• put that next to free space on the volume. shrinking disk and growing swap at the same time is the disk case, and it does not need a percentage to be obvious.

and the space is usually not where you would look for it — caches, iOS backups and local snapshots rather than your own files: what the space a cleaner finds is made of

Apple's own list of where the space goes is the place to start: free up storage space on Mac — Apple Support

what to do when your system has run out of application memory

1. in the dialog itself, quit the app at the top of the list — macOS sorts it by what is using the most, and it is usually right.
2. sort the Memory tab by that column and look for something absurd. a browser holding a lot across many tabs is normal; one process holding thirty gigabytes is not.
3. free disk space if that was the diagnosis. swap needs room, and a drive with a couple of gigabytes left cannot provide it.
4. check the process is not simply doing its job — an export, a build, a big import legitimately needs the memory, and the answer is to wait.
5. restart last, once you know what caused it. it always works and it destroys the evidence.

so, the short version. if the dialog names one app, quitting it fixes your afternoon and it does not come back — you are finished, and nothing here needs installing. the simple case ends the moment the message returns and you cannot say what preceded it. by then what you need is not a reading, it is the hour before the reading, and neither Activity Monitor nor sysctl keeps one.

how hop warns before you run out of application memory

hop's monitor keeps the memory row in the panel with everything else — load, temperatures, network, disk, battery, power draw, uptime — and it is quiet until something is worth looking at. values light up when they leave the range you consider normal, and you set what normal is.

everything the monitor reads, what the thresholds do, and what it costs to run: the system monitor

the third row is the one that matters. «it climbed all morning» and «it jumped when I opened that file» are different diagnoses, and an hour of graph separates them without you having been at the desk. hop itself barely uses any resources, which for a thing that watches memory is not a small requirement.

worth being clear about what it is not: nothing here frees memory, and an app that offers to is either quitting your programs or emptying caches the system was using on purpose. the useful thing a monitor does is tell you which of the three cases above you are in.

temperature is the reading macOS hides completely on Apple silicon, and it sits in the same rows: check cpu temperature on Apple silicon

when out of application memory keeps coming back

• the same app every time. it is leaking — update it, and if it is current already, that is a bug report rather than a Mac problem.
• it is one of the usual names. the forum threads keep landing on the same few: Chrome, where every tab is a process of its own; Photoshop and Lightroom Classic; Premiere Pro; Logic Pro with a lot of instruments loaded; and Mail, which several people watched climb while it sat idle.
• you are on macOS 26. this one deserves separating from your own Mac: the Tahoe threads describe memory leaking in system processes — IconServicesAgent is named again and again — on machines with far more ram than the work needs. if the process holding it is not one you launched, it is not your setup, and freeing disk space will not fix it.
• it started after an update. a new version of one app can change its appetite entirely — check that one before suspecting the Mac.
• it happens with the lid closed overnight. a sync, an indexer or a backup is running while you are not there, and an hour of graph will name it.
• you have 8 gb and you edit video. this is the case where the message is simply true, and no setting changes it.
• «force quit» does nothing and the Mac is frozen. hold the power button. an unsaved document is a smaller loss than the hour it will otherwise take.

the macOS 26 threads are the best record of this, because people post their actual numbers: macOS 26 Tahoe: system runs out of application memory — Apple Community

and developers comparing the same apps across releases keep their own thread: memory consumption of apps under macOS 26 — Apple Developer Forums

if something is running while you are not there, the fans usually said so before the dialog did: why your Mac fan is loud

if the diagnosis came out «the disk is full» and you cannot find the space: what system data is actually using

frequently asked questions

why does my Mac say it is out of memory when i have plenty of ram?

because swap has nowhere to go. macOS pushes memory it is not actively using onto the disk, and if the disk is nearly full that stops working — the message follows regardless of how much ram is installed.

how do i check swap usage on a Mac?

sysctl vm.swapusage in Terminal, no password. one line, three numbers: total set up, used, and free inside what is already reserved. Activity Monitor shows the same figure as Swap Used at the bottom of the Memory tab.

where is the swap file on a Mac?

in /System/Volumes/VM/, as files named swapfile0, swapfile1 and so on; ls -lh /System/Volumes/VM/ lists them with sizes and dates. they come in whole gigabytes, so counting them gives you the same total sysctl reports.

how much free disk space does macOS need for swap?

Apple documents no figure. the usual answers — ten percent, fifty to a hundred gigabytes, as much as your ram — trace back to vendor pages and forum replies, not to Apple. macOS adds a gigabyte of swap when it wants one and stops when the volume refuses.

will more ram fix it?

only if memory pressure is genuinely red with little swap in use. if the disk was the constraint or a process was leaking, more ram delays the same dialog rather than preventing it.

what is memory pressure?

macOS's own summary of how hard it is working to keep everything supplied — green, amber, red. a better signal than «memory used», which is always high on purpose: unused ram is wasted ram. the colours live in Activity Monitor only, and the memory_pressure command prints counters rather than a level.

is it safe to force quit the app it names?

yes, with the usual cost of unsaved work. the dialog sorts by consumption, so the app at the top is normally the right one to close.

do memory cleaner apps help?

not meaningfully. freeing memory the system deliberately filled with caches makes the next few minutes slower. what helps is finding the process, or finding the disk space.

the tool behind this

done with system monitor

other things people do

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