How to free up RAM on a Mac without restarting

macOS is good at managing memory, which is why the Memory tab in Activity Monitor is confusing: "Memory Used" is always near the total, and that is fine. What matters is the Memory Pressure graph at the bottom. Green is healthy. Yellow means the Mac is compressing memory. Red means it is swapping to disk and everything stutters.

Find what is eating it

Open Activity Monitor → Memory and sort by the Memory column. The usual suspects on a developer Mac: Xcode with a large project (8 GB and more), Simulator, Docker (it reserves whatever you gave it in its settings), Chrome or Brave with dozens of tabs, and Slack or Teams. Each simulator you have booted costs 1 to 2 GB even when idle.

Release memory now

1. Quit the big ones properly (Cmd+Q), not just close their windows. Browser tabs count: close the ones you have not touched today.
2. Shut down simulators you are not using: Simulator → Device → Erase All Content and Settings is not needed, just quit the Simulator app.
3. Purge inactive memory. macOS keeps recently used files cached in RAM and only drops them when pressure rises. The command below forces that drop:

sudo purge

The effect is immediate: the cached files are released and the pressure graph drops back to green. The files are read from the SSD again when needed, which on an Apple Silicon Mac is barely noticeable.

Do it without Terminal

Free My Disk has a Free RAM button that relieves memory pressure the same way, next to the disk cleanup it is mainly known for. It is handy on a laptop with 8 GB where Xcode, a simulator and a browser together already hit the ceiling.

Stop it from coming back

• Lower the memory Docker reserves (Docker → Settings → Resources). The default is far above what most projects need.
• Remove login items you do not use (System Settings → General → Login Items).
• If pressure is red every day with your normal workload, no trick helps: the next Mac needs more memory. 16 GB is the sensible minimum for iOS development in 2026.