File size


File size is a measure of how much data a computer file contains or, alternately, how much storage it consumes. Typically, file size is expressed in units of measurement based on the byte. By convention, file size units use either a metric prefix or a binary prefix.
When a file is written to a file system, which is the case in most modern devices, it may consume slightly more disk space than the file requires. This is because the file system rounds the size up to include any unused space left over in the last disk sector used by the file. The wasted space is called slack space or internal fragmentation. Although smaller sector sizes allow for denser use of disk space, they decrease the operational efficiency of the file system.
The maximum file size a file system supports depends not only on the capacity of the file system, but also on the number of bits reserved for the storage of file size information. The maximum file size in the FAT32 file system, for example, is 4,294,967,295 bytes, which is one byte less than four gibibytes.
Kilobyte , is sometimes referred to unambiguously as kibibyte. Sometimes kB, with lower cased SI-prefix 'k-' for kilo, is used, then always equaling 1000 bytes.
A file system may display all sizes with the metric system with only 'kB' on small files indicating it, while some file systems/operating systems would display sizes in, the traditionally used on computers, binary system for all sizes, e.g. 'KB', while hard disk manufacturers use the metric system.
File transfers may use rates of units of bytes in binary rather than metric system, while networking hardware, such as WiFi, always uses the metric system. of units of bits, making superficially similar terms very incompatible.