Softset

Performance

What Mac memory pressure means

Updated · Applies to macOS 14 Sonoma through macOS 27 Golden Gate

Short answer

Memory pressure shows how hard macOS is working to find memory for your apps. Green means there's enough. Yellow means it's compressing memory to cope. Red means it's also writing memory to disk (swap), which slows everything down.

Your Mac will almost always report that most of its memory is “used”. That’s by design: macOS keeps recently used files and data in spare memory so things open faster, and hands that memory back instantly when an app needs it. So “memory used” doesn’t tell you much. Memory pressure does.

How macOS finds more memory

When apps ask for more memory than is free, macOS works through three steps, from cheapest to most expensive:

  1. Reclaim caches. Throw away cached file data. Nearly free.
  2. Compress. Squeeze memory apps haven’t touched recently. Costs a little processor time.
  3. Swap. Write memory out to the disk and read it back when it’s needed. Even on a fast SSD this is much slower than RAM.

Memory pressure reflects how far down that list macOS has had to go.

Green, yellow, red

Green
macOS is getting the memory it needs from free memory and caches. You don’t need more RAM for what you’re doing.
Yellow
macOS is compressing memory to keep up. Usually still fine, but it’s a sign you’re near the limit.
Red
macOS is swapping heavily. Apps pause, the beachball appears, and switching apps feels slow.

Where to see it

In Activity Monitor → Memory, the graph at the bottom. In Terminal:

memory_pressure | tail -1   # "System-wide memory free percentage"
sysctl vm.swapusage          # how much swap is in use

When pressure is high