
Marco Arment: "Everyone should play by the same rules.
A proposal: storage capacities referenced or implied in the names or advertisements for personal computers, tablets, and smartphones should not exceed the amount of space available for end-user installation of third-party applications and data, after enough software has been installed to enable all commonly advertised functionality. With today's OSes, iPads could advertise capacities no larger than 12, 28, 60, and 124 GB and the Surface Pros could be named 23 and 83 GB." Wholly agreed. When I buy a box of 100 staples, I expect it to contain ~100 staples - not 50 because the other 50 are holding the box together.
Member since:
2006-10-08
So first we have: 1000 vs. 1024 factor.
Furthermore: total vs. usable disk space.
To extend this idea, you could the consideration of "gross available disk space" vs. "net available disk space", where "gross" refers to actually usable "bytes in storage" (hard disk or SSD), and "net" refers to capacity to be used or occupied by actual user data. This means, "gross" includes metadata for storing user data, and "net" includes only the user data (music files, image files, movie files and so on). So data written to disk (from the "usable disk space" portion) can be treated including or excluding file system overhead, journaling data, checksums, indexing metadata and so on.
So for your actual files, you can mention the exact space available by subtracting the "non-user usable" occupation of the disk (mostly operating system) and the management overhead (mostly file system metadata) and then apply the correct SI or 2^10 unit prefix.
;-)