Data Storage

How do we measure the data storage in a computer?

A computer stores information in binary format. The Binary system is a number system which uses bits to store data. A bit is a “binary digit”, the smallest increment of data on a machine. A bit can hold only one of two values: 0 or 1.

Because bits are so small, you rarely work with information one bit at a time. Bits are usually assembled into a group of 8 to form a byte or "binary term". Computer memory is typically byte addressed – each byte has a unique address.

Bytes are often used to store characters (they contain enough information to store a single character), but they can also be used to store numerical values.

A byte can store a numerical value between 0 and 255 or between -127 and 127 if we are considering the negative numbers too.

There are 2⁸ = 256 different byte values:

Bit values

For the purposes of storing numerical data values, bytes are grouped together into words, which are typically 2 bytes.

short int, unsigned short	16 bits (2 bytes)
int, unsigned int	32 bits (4 bytes)
long int, unsigned long	32 or 64 bits (4 or 8 bytes)

Data type definition

Data units of 512 bytes or more are called data blocks. Each operating system has a specific block size.

1 byte	8bits
1 kilobyte	210 bytes	1’024 bytes
1 megabyte	220 bytes	1’048’576 bytes
1 gigabyte	230 bytes	1’073’741’824 bytes
1 tetrabyte	240 bytes	1’099’511’627’776 bytes

Conversion table