What is wired memory on a Mac?

Wired memory is memory that macOS has locked in place and cannot compress or move out to the disk. It holds the parts of the system that must always be instantly available, such as the core of macOS and the drivers that talk to your hardware, and on Apple silicon Macs it also includes graphics memory that apps are using. Some wired memory is on every Mac and is normal. You cannot free it by hand, and you do not need to.

The word gets worrying when it shows up in a memory readout next to “free” and “used”. This post explains what it is, how to see your own figure, and the few cases where a high number is worth a look.

What “wired” means

Memory on a Mac is handed out in blocks called pages. For most pages, macOS has choices. If an app has not touched a page in a while, macOS can compress it to make room, and if it still needs room it can write the page to the disk (swap) and bring it back later. That flexibility is how a Mac runs more than fits in memory at once.

A wired page has none of those choices. It is pinned in place. It cannot be compressed or swapped out. The reason is practical: some code and data have to be reachable at any instant, even at moments when the Mac could not safely stop to read from the disk. If the part of the system that reads from the disk were itself stored on the disk, nothing would ever get started.

What is in it

A large share belongs to the kernel, which is the core of macOS, and to the drivers it loads for your hardware. In a process list that core appears as kernel_task, which Foreman labels “macOS kernel”. Apps and system services can also ask for pages to be wired, usually for time-critical data.

On an Apple silicon Mac, the processor and the graphics chip share the same memory, and memory an app holds for graphics is counted as wired while the app is using it. A game, a video or 3D editor, or an AI model running on the Mac can therefore raise the wired figure a lot, and quitting that app gives its share back.

Wired memory is a system-wide total, not something that has its own row you can end. You will not find a process called “wired memory” to quit, and quitting an ordinary app such as a browser or a word processor barely changes it.

Where to see your figure

Foreman shows memory with its memory pressure under Memory on its Performance page, with the apps using the most listed under it. For the wired figure itself, use Terminal.

• Run top -l 1 | grep PhysMem. The line it prints gives the memory in use and, in brackets, how much of it is wired and how much the compressor holds.
• Run vm_stat for a page-by-page breakdown. The first line states the page size, and the line “Pages wired down” gives the count of wired pages. Multiply that count by the page size to get bytes.

Both only read information. Neither changes anything.

What is a normal amount

There is no single normal figure, and I will not invent one. It depends on the Mac, the version of macOS, which drivers are loaded, how much you have connected, and on Apple silicon, which apps are using graphics memory at the moment. A Mac with external displays, an audio interface and a game or 3D app open will wire more than the same Mac sitting at the desktop.

A better test than a number is stability. Look at your wired figure after a fresh restart, then again after a few days of work, with the same apps open each time. A figure that stays within a fairly narrow range is normal. A figure that keeps climbing day after day, with nothing new open, is worth investigating.

Is a high wired figure a problem

Mostly no. A high figure is not a sign of a leak by itself. What matters is what is left over for everything else.

Wired memory is part of the total. The more of your memory is locked, the less is left for apps, and the sooner the Mac has to compress and swap what remains. So a large wired figure on a Mac with modest memory can push memory pressure up sooner than the same figure on a Mac with plenty. If pressure is low, ignore the wired figure. If pressure is high, look at wired as one contributor among others.

Memory pressure on a Mac: when you actually need more RAM explains how to read pressure, and Compressed memory on a Mac, explained covers the layer between wired and swap.

When wired memory keeps growing

Two things can cause a figure that grows and stays grown.

A driver with a problem. Software that adds pieces to the core of macOS, such as some virtual drive, network filter, audio and virtualization tools, can hold on to more wired memory over time if it has a bug. If wired memory started climbing after you installed something like that, that is your suspect. Updating it, or checking its maker’s site, is the first step. Removing it is the test: if the figure stops climbing, you have your answer.

A very long uptime. Some Macs run for weeks without restarting. Restarting starts the wired figure from scratch, and it is a free, safe step. If the figure starts low and climbs again over the same period, the pattern points back to the first cause.

What not to do is chase it with a tool that promises to free memory. Wired memory is released only by whatever locked it, and a tool claiming to free memory would only push other memory around, which macOS already does by itself.

What you can do about it

1. Check pressure first. If pressure is low, you are done.
2. If pressure is high and wired is large, look at what you have installed that talks to hardware or the network at a low level. Update or remove what you no longer use.
3. Quit apps that use a lot of graphics memory when you are done with them, then restart if the figure is still high. A restart starts the count from scratch.
4. If the figure still grows from a fresh start with nothing unusual installed, note which app you ran before it grew and test without it. If you find a pattern, contact the app’s maker.

Do not try to end kernel_task. macOS does not let you, and Foreman will not offer it either. What is kernel_task on a Mac, and why does it use so much CPU? explains that process.

Summary

Wired memory is the part of your memory that macOS pins in place so it is always instantly available. It cannot be compressed or swapped, it is not something to free, and some of it is on every Mac. Worry about it only if it climbs without stopping, or if memory pressure is high and a large share of your memory is locked. For why a Mac can seem to use a lot with nothing open, see Why does my Mac use so much memory with nothing open?.