The basic units of data storage are as follows:

1. Bit: Computer works with binary digits. These digits are in the form of 0’s and 1’s. A binary digit is called bit. One bit takes one storage location in memory. It is the smallest unit for data storage.

2. Byte: A collection of eight bits is called byte. It is used to store single character. The capacity of the memory or the storage is expressed in terms of bytes.

3. Kilobyte: A kilobyte consists of 1024 bytes. It is denoted by KB.

4. Megabyte: A megabyte consists of 1024 kilobytes. It is denoted by MB.

5. Gigabyte: A gigabyte consists of 1024 megabytes. It is denoted by GB.

6. Terabyte

A terabyte consists of 1024 gigabytes. It is denoted by TB.

The commonly used storage capacity terms are as follows:


7. Word

A computer word is the number of bytes in common unit of data defined by the computer system. It is normally the size of a register. The length if a word is different in different computers. The larger word indicates more powerful computer.

The following tables indicates different word sizes:

Ear of computer

No. of bits

No. of bytes

Very early personal computer


One byte

Traditional micro-computer


Two byte

Mainframe, mini-computer and microcomputers


Single word

Super computers and some micro computers


Double word

Q. Convert 240MB of memory in bytes and kilobytes.