The short answer
Application memory on a Mac is the memory your apps and their background processes are using. Activity Monitor shows it as App Memory in the Memory tab, beside Wired Memory, Compressed and Cached Files. A high figure is normal. Worry only when the Memory Pressure graph turns yellow or red and Swap Used keeps growing: quit the app that grew.
On this page
What application memory is
Apple defines App Memory in Activity Monitor as the amount of memory being used by apps. That includes the helper processes apps run in the background: a browser's tab processes, an editor's language servers, a chat app's renderers. It's the part of the Mac's memory you control. Quit an app or close tabs and it falls.
A large figure isn't a fault. macOS hands spare memory to apps that ask for it and makes room when it needs to, first by compressing memory, then by writing it to swap on the startup disk. Whether that's happening is what memory pressure tells you.
Application memory vs wired, compressed and cached memory
Activity Monitor's Memory tab lists these figures under the Memory Pressure graph. Memory Used is split into App Memory, Wired Memory and Compressed; Cached Files and Swap Used are shown on their own lines.
| Figure | What it is | What you can do about it |
|---|---|---|
| App Memory | Memory being used by apps and their processes. | Quit apps or close tabs you aren't using. macOS can also compress it or move it to swap. |
| Wired Memory | Memory the system needs to operate. It must stay in RAM. | Nothing directly. It's released when the work that holds it ends. |
| Compressed | Memory macOS has compressed to make more RAM available. | Nothing. It's macOS making room; a growing figure is an early sign that something is growing. |
| Cached Files | Files cached by the system into unused memory to improve performance. | Nothing. macOS gives it to apps the moment they need it. |
| Swap Used | Space on the startup disk used to swap memory to and from RAM. | Watch whether it keeps growing. Flat swap is fine. |
App Memory
- What it is
- Memory being used by apps and their processes.
- What you can do about it
- Quit apps or close tabs you aren't using. macOS can also compress it or move it to swap.
- What it is
- Memory the system needs to operate. It must stay in RAM.
- What you can do about it
- Nothing directly. It's released when the work that holds it ends.
- What it is
- Memory macOS has compressed to make more RAM available.
- What you can do about it
- Nothing. It's macOS making room; a growing figure is an early sign that something is growing.
- What it is
- Files cached by the system into unused memory to improve performance.
- What you can do about it
- Nothing. macOS gives it to apps the moment they need it.
- What it is
- Space on the startup disk used to swap memory to and from RAM.
- What you can do about it
- Watch whether it keeps growing. Flat swap is fine.
The difference that matters: app memory can be squeezed and moved, wired memory can't, and cached files are given back straight away. The wired memory entry goes deeper on the one part macOS can't reclaim.
How to read application memory in Activity Monitor
- Open Activity Monitor, in Applications → Utilities, or search for it with Spotlight.
- Click Memory at the top of the window.
- Read the panel at the bottom: the Memory Pressure graph on the left, and Physical Memory, Memory Used, Cached Files and Swap Used next to it, with App Memory, Wired Memory and Compressed beside Memory Used.
- Click the Memory column heading to sort processes by memory, largest first.
- To see how much of each process macOS has compressed, add the Compressed Memory column with View → Columns.
The same figures in Terminal
top -l 1 | grep PhysMem
memory_pressure | tail -1
sysctl vm.swapusagePhysMem: 15G used (3263M wired, 7362M compressor), 72M unused.
System-wide memory free percentage: 31%
vm.swapusage: total = 19456.00M used = 18971.69M free = 484.31M (encrypted)top calls compressed memory “compressor” and doesn't list app memory on its own line. Almost no memory is unused, which is normal: macOS fills spare memory with cached files. The swap figure is large because macOS leaves memory in swap until something needs it again, even after the pressure has passed. What matters is whether it keeps growing while you work.
When high application memory is a problem
Judge it by the Memory Pressure graph, not the App Memory figure. Apple describes the colours like this:
| Memory pressure | Apple's description | What to do |
|---|---|---|
| Green | The Mac is using all of its RAM efficiently. | Nothing, however large App Memory is. |
| Yellow | The Mac might eventually need more RAM. | Find the app that grew and quit or restart it if you can. |
| Red | The Mac needs more RAM. | Save your work, then quit the apps using the most memory. Swap Used will usually be growing. |
Green
- Apple's description
- The Mac is using all of its RAM efficiently.
- What to do
- Nothing, however large App Memory is.
Yellow
- Apple's description
- The Mac might eventually need more RAM.
- What to do
- Find the app that grew and quit or restart it if you can.
Red
- Apple's description
- The Mac needs more RAM.
- What to do
- Save your work, then quit the apps using the most memory. Swap Used will usually be growing.
Apple also notes that free memory doesn't by itself make the Mac faster, which is why “free up RAM” tools don't help. The memory pressure guide walks through a slowdown step by step.
Why application memory is high, and what to do
- Browsers with many tabs. Each tab and extension can run in its own process. Close tabs you aren't using, or use the browser's own memory saving setting.
- Virtual machines, containers and simulators. They reserve memory for a whole operating system. Shut them down when you've finished with them.
- Language models running on the Mac. A model loaded into memory stays there until it's unloaded. See how much memory Ollama uses.
- Apps that grow over hours. Some apps keep using more memory the longer they're open. Quitting and reopening gives it back.
- Forgotten background work. Dev servers, watchers and build tools left running from earlier. See kill leftover dev servers.
- Sort the Memory tab by Memory and note the apps at the top.
- Watch it for a few minutes. An app that keeps climbing matters more than one that's large and steady.
- Quit or restart the app that grew. Its memory is released when it quits.
- Check the Memory Pressure graph again. If it's back to green, you're done.
- If pressure is yellow or red every day with your usual apps, the Mac needs more memory than it has for that work. Apple's guide shows how to check whether your Mac's memory can be upgraded; on Apple silicon Macs it can't.
“Your system has run out of application memory”
macOS shows this message when apps need more memory than it can find room for, in RAM or in swap. Quit an app you aren't using from the list it shows, then save your work in the rest. Because swap lives on the startup disk, a nearly full disk makes the message more likely: check System Settings → General → Storage, and see why free space numbers disagree if they don't add up.
The faster way: memory by app in iKnowMyMac
iKnowMyMac's Memory tab breaks memory into App, Wired, Compressed, Cached and Free, and lists apps rather than processes, so a browser's helpers add up to one row with one total. The Memory screen names the app that grew, with how much, in the line under its verdict.