Take Away: From bit to exabyte, know your quantities.
KB100978
Confused by megabit versus megabyte versus a Terabyte? These are actually pretty easy to understand if you break them down into units and prefixes. The units are bit and byte. The prefixes we'll focus on or kilo, mega, giga, tera, peta, and exa.
Bit and Byte
Bit (lowercase "b") A binary digit, a single, basic unit of information, used in connection with computers and information theory. A bit is usually represented by a 0 or 1 but can also be represented by anything that can represent on and off. For example, the divits in the surface of a CD.
Byte (uppercase "B") Adjacent bits, usually eight, processed by a computer as a unit. The combination of bits used to represent a particular letter, number, or special character. Early in computer science history (in the 1950s), computers used 3 and 6 bit bytes. The standard 8-bit byte standardized starting in the late 50s.
Common Units Table
Now that you understand the fundamentals, the following table will make better sense to you.
Unit
Abbrev.
In Bits
Formal
Informal
Notes
Bit
b
1
N/A
A binary digit, a single, basic unit of information, used in connection with computers and information theory. A bit is usually represented by a 0 or 1 but can also be represented by anything that can represent on and off. For example, the divits in the surface of a CD.
kilobit
kb
1000 x 1
megabit
mb
Byte
B
8 x 1 bit
1
Adjacent bits, usually eight, processed by a computer as a unit. The combination of bits used to represent a particular letter, number, or special character.
KiloByte
KB
210 x 8 bits
1,024 bytes
1,000 bytes
Sometimes used loosely and imprecisely as 1000 bytes.
Megabyte
MB
220 x 8 bits
1,024 kilobytes.
1,000 kilobytes
Sometimes used loosely and imprecisely as 1 million bytes. In computer science and industry usage, the prefix mega- often does not have its standard scientific meaning of 1,000,000, but refers instead to the power of two closest to 1,000,000, which is 220, or 1,048,576.
Gigabyte
GB
230 x 8 bits
1,024 megabytes.
1,000 megabytes
Also known as 1,000 Megabytes. Sometimes used loosely and imprecisely as 1 billion bytes. Roughly the amount of data required to encode a human gene sequence (including all the redundant codons).
Terabyte
TB
240 x 8 bits
1,024 gigabytes.
1,000 gigabytes
Also known as 1,000 Gigabytes. Sometimes used loosely and imprecisely as 1 trillion bytes.
Petabyte
PB
250 x 8 bits
1,024 Terabytes
1,000 petabytes
Also known as 1,000 Terabytes. Sometimes used loosely and imprecisely as 1 quadrillion bytes.
Tech
Print This
