Understanding file sizes (Bits, Bytes, KB, MB, GB, TB)

Have you ever been confused about the number of kilobytes in a megabyte, or in a gigabyte or vice-versa?

These terms are those used most commonly and is the binary system, and you can be comfortable using it. The binary system is a base 2 system in which a bit is a binary digit, the smallest increment of data on a computer. A bit can hold only one of two values: 0 or 1. Put another way, a bit is either an 'on' or an 'off' which is processed by a computer processor, we represent 'on' as '1' and 'off' as '0'. 8 bits are known as a byte, and it is bytes which are used to pass our information in it's basic form - characters.

An alphanumeric character (e.g. a letter or number such as 'A', 'B' or '9') is stored as 1 byte. For example, to store the letter 'R' uses 1 byte, which is stored by the computer as 8 bits, '01010010'. Note that many non-alphanumeric characters such as symbols and foreign language characters use multiple bytes

A kilobyte (KB) is 1,024 bytes, not one thousand bytes as might be expected, because computers use binary (base 2) math, instead of a decimal (base 10) system.

Computer storage and memory is often measured in megabytes (MB) and gigabytes (GB). Where 1 MB is 1,024 kilobytes, or 1,048,576 (1024x1024) bytes.

Similarly, one 1 GB is 1,024 MB, or 1,073,741,824 (1024x1024x1024) bytes. A terabyte (TB) is 1,024 GB; 1 TB is about the same amount of information as all of the books in a large library, or roughly 1,610 CDs worth of data. A petabyte (PB) is 1,024 TB. Indiana University is now building storage systems capable of holding petabytes of data. An exabyte (EB) is 1,024 PB. A zettabyte (ZB) is 1,024 EB. Finally, a yottabyte (YB) is 1,024 ZB.

So in computer jargon, the following units are used:

UNIT EQUIVALENT 1 kilobyte (KB) 1,024 bytes 1 megabyte (MB) 1,048,576 bytes 1 gigabyte (GB) 1,073,741,824 bytes 1 terabyte (TB) 1,099,511,627,776 bytes 1 petabyte (PB) 1,125,899,906,842,624 bytes

Since your computer uses a binary system as mentioned above, you may notice a discrepancy between your hard drive's published capacity and the capacity acknowledged by your computer. For example, a hard drive that is said to contain 10 GB of storage space using a decimal system is actually capable of storing 10,000,000,000 bytes. However, in a binary system, 10 GB is 10,737,418,240 bytes. As a result, instead of acknowledging 10 GB, your computer will acknowledge 9.31 GB. This is not a malfunction but a matter of different definitions.