Formatted capacity (why 128GB shows less)
Also known as: why my phone shows less storage, advertised vs actual storage, usable capacity
Formatted capacity is the usable space a device actually reports, which is always less than the advertised number. The gap comes from two things: marketers count a gigabyte as 1,000,000,000 bytes while many systems count 1,073,741,824 (a GiB), and the operating system itself occupies part of the drive.
- Advertised GB (decimal) vs displayed GiB (binary) differ
- A 128 GB drive shows roughly 119 GiB before the OS
- The operating system also occupies part of the drive
Why advertised and usable differ
Storage is sold in decimal units, where 1 GB equals one billion bytes. Many devices, however, display capacity in binary units (gibibytes), where 1 GiB equals 1,073,741,824 bytes. Dividing the same chip by the larger binary unit yields a smaller-looking number — so a "128 GB" drive shows roughly 119 GiB before anything is installed.
On top of that unit mismatch, the operating system, recovery partition, and preinstalled apps live on the same drive. That pre-used space further lowers what is free out of the box.
What this means in practice
Nothing is missing or broken — this is expected and consistent across phones, tablets, and computers. The advertised figure describes the raw chip; the device shows usable space after the unit conversion and system overhead.
When comparing devices, look at the usable or available figure shown in settings rather than the box number, since that reflects the space you can really fill.