How to check your Mac's SSD health and wear
An SSD can only be written so many times. On most Macs the SSD is built in and can't be replaced, so it's worth knowing how worn yours is.
The short answer: macOS only shows "S.M.A.R.T. status: Verified". The real figures are in the drive's own health log: Percentage Used (how much of its rated write endurance is used), Data Units Written and any media errors. You can read them with smartctl.
Where does macOS show SSD health?
Hold Option and choose Apple menu › System Information, then Storage or NVMExpress. You'll see "S.M.A.R.T. status: Verified". That only means the drive doesn't predict a failure; it says nothing about wear.
How do I see SSD wear in Terminal?
Install smartmontools with Homebrew, then read the internal drive:
brew install smartmontools
smartctl -a disk0In the output, look for:
- Percentage Used: the share of the drive's rated write endurance used up.
- Data Units Written: everything written so far. Each unit is 512,000 bytes, so 100,000,000 units is about 51 TB.
- Available Spare: reserve blocks left, starting at 100%.
- Media and Data Integrity Errors: should be 0.
What does Percentage Used mean?
The maker rates the drive for a total amount of writes. Percentage Used is how much of that rating you've used. 100% means the rating is reached, not that the drive stops: many keep working well past it, and the figure can go above 100. A few percent a year is normal; a fast climb is a sign something writes a lot.
What wears out a Mac's SSD?
- Swap: when memory runs short, macOS writes it to the SSD, all day. Check it with
sysctl vm.swapusageor in Activity Monitor › Memory (Swap Used). Several GB of swap most of the time means the Mac needs more memory than it has for what you run. - Large builds, virtual machines and Docker, and downloading big files or AI models again and again.
Can every Mac report SSD wear?
Macs with an NVMe drive can: Apple silicon Macs and most recent Intel Macs. Some older Intel Macs with a SATA SSD don't report these figures.