Why Mac Book Air (M1) shows only 500 GB instead of 512 GB storage?

Hi Ola_909,

Please complete these steps to describe the layout of your internal disk. Once that's done, I can check whether it is configured correctly to utilize all of the space.

1. Open Terminal, located in Applications -> Utilities.
2. Type this command and hit Enter (Return): diskutil list
3. Post the output here.

The 512 is a manufacturing raw spec. and not the formatted spec. After formatting the volume shown can be less. If you want a more detailed explanation please look at this article:

https://www.crucial.com/support/articles-faq-ssd/ssd-showing-smaller-than-advertised

tbirdvet wrote:

The 512 is a manufacturing raw spec. and not the formatted spec. After formatting the volume shown can be less. If you want a more detailed explanation please look at this article:

https://www.crucial.com/support/articles-faq-ssd/ssd-showing-smaller-than-advertised

Good point, but macOS seems to report disk usage on the 1000 scale (kilobytes, megabytes, gigabytes, terabytes, etc.), rather than the binary scale (kibibytes, mebibytes, gibibytes, tebibytes, etc).

If macOS was reporting on the binary scale like Windows, 512 GB ~= 476.8 GiB. (512000000000 bytes / [1024^3] bytes)

One thing with SSDs, there is a thing called over provisioning. SSD locations can only be written to so many times. When you can't write to a particular location anymore it is removed from use and a section from the over provisioned area is then used.

With a 512GB SSD, for an example, you may only have 500GB usable space because the extra 12GB is put into this over provisioning area. Then it comes down to an advertising numbers game. If a manufacturer only advertises the drive as 500 GB (or in some cases 480 GB), it may not draw as much as saying it is a 512GB drive.