Swap on a Mac: How Much Is Normal and When to Worry

Swap on its own is not a problem: if the Memory Pressure graph is green and Swap Used stays put, all is fine. It’s a signal when swap keeps growing while the graph turns yellow or red.

Open Activity Monitor, switch to the Memory tab, and at the bottom you’ll see “Swap Used: 6.2 GB”. Six gigabytes on disk instead of in RAM sounds like bad news for both the Mac and its SSD.

What swap is

When memory starts running short, macOS first compresses data that hasn’t been used for a while, right there in RAM — that’s the Compressed line. If that’s not enough, compressed data goes out to swap files on the startup disk. That’s swap. Apple’s guide describes Swap Used as the space on your startup disk used to swap unused files to and from RAM.

The swap files live on a separate system volume, /System/Volumes/VM, and they are encrypted. Compression, cache and the graph colors are covered in the memory pressure guide; this one is about swap only.

How much is normal

Apple publishes no “over 4 GB is bad” threshold, and there’s no point inventing one: the same number means different things on 8 GB and on 64 GB of RAM. Look at the combination:

• Memory Pressure graph green, swap standing still — all fine. At some point macOS moved out things that weren’t needed and isn’t going back for them. Let them sit there;
• graph yellow, swap growing — there isn’t enough memory for this work. The system keeps shuffling data between RAM and disk, which is where the short stalls when switching windows come from;
• graph red — the slowdown is happening now; time to close something.

While the Mac runs without a restart, swap can slowly build up: things you haven’t touched in a long while move out. If it then stays put, that’s not a leak.

Is swap growing? How to check

The easiest way: note the Swap Used number in the morning and look again in the evening after a normal day. It went from 1 to 7 GB and the graph was yellow during the day — that’s a signal. It was 5 and it’s still 5 — nothing is happening.

For the curious, in Terminal:

• sysctl vm.swapusage prints one line: how much swap space is allocated (total), used (used) and free (free). The (encrypted) at the end is that encryption;
• vm_stat includes the Swapouts and Swapins lines: how many compressed pages have been written to disk and read back since startup. Run it twice an hour apart. If Swapouts has barely moved, swap is standing still, however large it is;
• vm_stat 60 prints the totals in the first line, then the increments every minute. Zeros in the swapins and swapouts columns mean the system isn’t going to disk. Stop it with Control-C.

Swap and the SSD

To be honest: writing to swap is writing to the SSD, and every SSD has a finite write endurance. But for normal work it’s no reason to panic. Howard Oakley, who writes about macOS internals on the Eclectic Light blog, looked at exactly this question (a 2022 article). He suggests checking what share of all writes to the disk goes to swap: under 10% and swap contributes little to wear; half or more, and more memory in your next Mac would noticeably extend the SSD’s life. Overall, in his estimate, even the busiest users don’t write enough to a Mac’s internal SSD to wear it out over its normal lifetime of about ten years.

The reason to think twice isn’t “6 GB of swap”. It’s a yellow graph and Swapouts climbing every day. Then you’re short on memory all the time, and what suffers first is speed, not the disk. How much has already been written to your SSD and how to check it is in the SSD wear guide.

Can you turn it off

There’s no supported switch. The swap files are created by a system service, and the methods passed around on forums require turning off System Integrity Protection (SIP) or changing boot arguments. That weakens the Mac’s security and leaves it in an unsupported configuration.

More importantly, you don’t need to. Without swap, macOS won’t get faster when memory runs out — it will have to quit apps instead. Swap is the emergency exit, not the cause of the slowdown.

What to do if swap keeps growing

1. Find what took the memory. On the Memory tab, click the Memory column header to bring the hungriest processes to the top.
2. Restart the culprit. An app that has been running for days often grows slowly and never gives memory back.
3. Close browser tabs you don’t need. Each tab often runs as its own process.
4. Keep free space on the startup disk. Swap needs somewhere to go.
5. Restart the Mac if none of that helped: apps start fresh and memory is freed.

If swap grows every day on ordinary work and the graph stays yellow for long stretches, it’s about how much RAM you have. How to check that over a week is covered in is 8 or 16 GB enough. For a tour of the tabs and columns, see the Activity Monitor guide.

In the app

To be clear up front: Mac Resources doesn’t show swap or memory pressure — not in the widgets, not in the menu bar item. There’s no process list either. For swap and the culprit, go to Activity Monitor.

What the app does offer alongside:

• the small Memory widget shows memory used as a percentage, a graph for the past hour and the amount like “24 of 128 GB”. It’s calculated the same way as Memory Used in Activity Monitor. The hourly graph makes it obvious when memory sits near the ceiling all day;
• the Disk widget shows how full the startup volume is. Swap needs free space, and the widget shows when it’s running low;
• the menu bar item shows the highest percentage of CPU, memory and GPU and turns red above 80%. If it’s showing the memory symbol, memory is the most used right now — a good moment to open the Memory tab.

If swap isn’t the problem and the Mac is still slow, walk through the step-by-step diagnosis.