Monitor RAM usage on macOS

Your Mac feels sluggish, apps are taking a beat to switch, and you suspect you’re out of RAM — but by the time you open Activity Monitor, the damage is done. macOS aggressively swaps to disk before it tells you anything’s wrong, so you usually only notice once everything’s already slow.

A live RAM readout fixes that. Here are your options.

Two paths

The native way (Activity Monitor)

Activity Monitor’s Memory tab is the official answer. The chart at the bottom shows Memory Pressure — green means you’re fine, yellow means macOS is starting to compress and swap, red means you’re in trouble.

The honest take: this works, but only if you’re already looking at it. You can pin it as an always-on-top floating window via Window > Memory Pressure, but it’s an extra panel cluttering your screen.

From Terminal, vm_stat 1 prints memory stats every second, and memory_pressure gives you a numeric pressure value. Both are accurate, both are awkward to leave running.

The Beacon way

Beacon puts memory usage and pressure in the menu bar so you see trouble building before it bites.

1. Install Beacon and open it from the menu bar.
2. Go to Settings > Menu Bar and enable Memory.
3. Choose what to show — used GB, percentage, or a pressure indicator that changes colour as pressure rises.
4. Click the memory readout to see a breakdown: app memory, wired, compressed, and swap used.
5. Watch the top memory processes list to spot the culprit when usage spikes.

The pressure-coloured indicator is the one I’d recommend leaving on — green most of the day means nothing to think about, and the moment it turns yellow you know to close some browser tabs before the rainbow wheel shows up.

Worth knowing: a Mac running at 90% memory usage isn’t necessarily struggling. macOS is happy to hold cached data in RAM if nothing else needs it. Pressure is the metric that matters, not raw usage.