The Glest Wiki

File size measures the size of a computer file. Typically it is measured in bytes with a prefix. The actual amount of disk space consumed by the file depends on the file system.

The maximum file size a file system supports depends on the number of bits reserved to store size information and the total size of the file system. For example, with FAT32, the size of one file cannot be equal or larger than 4 GiB.


The base unit for measuring filesize is the byte, which consists of 8 bits (a single switch of either a 0 or a 1). The reason for byte being the standard is due to the fact it was the amount of file size used by a single ASCII character. Prefixes allow the byte to be versatile enough for larger file sizes.

Powers of two versus powers of ten[]

There are two ways to measure filesize. Using a single capital letter prefix officially means that it is a power of 10, which is the standard for SI units, such as a kilobyte (KB) being 1000 bytes. However, the generally accepted method in computing using powers of two, since bytes are a binary format.

Since "kilo", "mega", etc are SI prefixes, they refer to the power of ten version. To allow the binary format to be properly referenced without confusion, their exists prefixes of "kibi", "mibi", etc, which refer to their power of two alternative.

On the Glest Wiki[]

On this wiki, generally the short form abbreviation is used (eg: KB), but actually refers to the power of two format. This short form abbreviation could be either type formatting, but is generally a power of two, as is standard with computing. If the long form is used (eg: KiB), then it is always a power of two.

Conversion table[]

Name Symbol Binary Measurement Decimal Measurement Number of Bytes Equal to
KiloByte / KibiByte KB / KiB 210 103 1,024 1,024 bytes
MegaByte / MebiByte MB / MiB 220 106 1,048,576 1,024 KB
GigaByte / GibiByte GB / GiB 230 109 1,073,741,824 1,024 MB
TeraByte / TebiByte TB / TiB 240 1012 1,099,511,627,776 1,024 GB

See also[]

Wikipedia logo.svg This page uses content from Wikipedia. The original article was at File size. The list of authors can be seen in the page history. As with the Glest Wiki, the text of Wikipedia is available under the Creative Commons Attribution-Share Alike License 3.0.