GaugeMon
Mac Performance Guide
Mac memory pressure yellow/red: what it means
Short answer
Memory pressure is macOS's own measure of how hard it is working to find memory. Green: fine. Yellow: macOS is compressing memory heavily and may be swapping; things can slow down. Red: apps need more memory than the Mac has, and it is swapping a lot. "Free memory" close to zero is normal and not the signal to watch.
Check it from the terminal
The current pressure level (1 is normal, 2 is warning, 4 is critical):
sysctl kern.memorystatus_vm_pressure_levelkern.memorystatus_vm_pressure_level: 2A summary. Run it with no arguments; its -l and -p options deliberately create memory pressure.
memory_pressure | tail -1System-wide memory free percentage: 44%How much swap is in use:
sysctl vm.swapusagevm.swapusage: total = 27648.00M used = 25983.69M free = 1664.31M (encrypted)And which processes are largest:
top -l 1 -o mem -n 10 -stats pid,command,memWhy free memory is misleading
On the same Mac, vm_stat reported only 46,253 free pages (about 720 MB of 48 GB, at 16 KB per page) while memory_pressure said 44% was available. macOS keeps otherwise idle RAM full of file cache it can drop instantly, and compresses memory before it swaps. So low free memory costs nothing; sustained yellow or red pressure and growing swap do.
- Quit the biggest entries from the
toplist, especially ones you are not using. - Lower memory limits for VMs and containers (Docker Desktop, emulators), which reserve large blocks.
- Close browser tabs; each one can hold hundreds of megabytes.
- If pressure is yellow or red during your normal work every day, the Mac needs more RAM for that work.
The easier way: GaugeMon
GaugeMon's Memory gauge sits in the menu bar as a value, ring or bar that can change colour when it is high. Click it for app, wired, compressed and cached memory, swap, a 10-minute chart and the five largest processes by physical footprint, the same measure Activity Monitor uses.
