Byte

A byte is a unit of measurement of the size of information on a computer or other electronic device. A single byte is usually eight bits. Some early computers used six bits for each byte. Bits are the smallest unit of storage on a computer, a single on/off value. Bytes are often represented by the capital letter B, bits by a lower case b.

A single typed character (for example, 'x' or '8') is stored in one byte. The character is held as a binary number which encodes a text character. To map each number to a character an agreed code such as EBCDIC or ASCII is needed. EBCDIC is a character encoding used mainly on mainframe computers. It uses 8 bits per byte. ASCII is another encoding that only uses seven bits. Extended ASCII uses 8 bits to give more types of characters, mostly used on personal computers.

The byte is the smallest useful unit of measure to show how many characters a computer (or electronics device) can hold. This is useful for things like RAM, or storage devices like USB drives and other types of Flash memory. Sending of data (for a modem or wi-fi) is usually measured in bits, not bytes.

On modern computers one byte is equal to eight bits. Some early computers used fewer bits for each byte. To tell them apart, computer scientists called an 8 bit byte an octet. In modern usage, an octet and a byte are the same.

Abbreviation

The symbol for "byte" is "B". Sometimes a lowercase "b" is used, but this use is incorrect because "b" is actually the IEEE symbol for "bit". The IEC symbol for bit is bit. For example, "MB" means "megabyte" and "Mbit" means "megabit". The difference is important because 1 megabyte (MB) is 1,000,000 bytes, and 1 megabit (Mbit) is 1,000,000 bits or 125,000 bytes. It's easy to confuse the two, but bits are much smaller than bytes, so the symbol "b" should be used when referring to "bits" and an uppercase "B" when referring to "bytes".

Names for larger units

For large data, byte is often used with a binary prefix:

• Kilobyte (kB) (10³)/kibibyte (KB) (2¹⁰)
• Megabyte (MB) (10⁶)/mebibyte (MiB) (2²⁰)
• Gigabyte (GB) (10⁹)/gibibyte (GiB) (2³⁰)
• Terabyte (TB) (10¹²)/tebibyte (TiB) (2⁴⁰)

The following terms represent even larger units of bytes, but are very rarely used:

• Petabyte (PB) (10¹⁵)/pebibyte (PiB) (2⁵⁰)
• Exabyte (EB) (10¹⁸)/exbibyte (EiB) (2⁶⁰)
• Zettabyte (ZB) (10²¹)/Zebibyte (ZiB) (2⁷⁰)
• Yottabyte (YB) (10²⁴)/Yobibyte (YiB) (2⁸⁰)
• Ronnabyte (RB) (10²⁷)/Robibyte (RiB) (2⁹⁰)
• Quettabyte (QB) (10³⁰)/Quebibyte (QiB) (2¹⁰⁰)

The following terms represent even larger unofficial units of bytes. (They are likely to never be used in future computing):

• Saganbyte (SB) (2¹¹⁰)
• Pijabyte (PjB) (2¹²⁰)
• Alphabyte (AB) (2¹³⁰)
• Pectrolbyte (PcB) (2¹⁴⁰)
• Bolgerbyte (BoB) (2¹⁵⁰)
• Sambobyte (SaB) (2¹⁶⁰)
• Quesabyte (QB) (2¹⁷⁰)
• Kinsabyte (KiB) (2¹⁸⁰)
• Rutherbyte (RB) (2¹⁹⁰)
• Dubnibyte (DB) (2²⁰⁰)
• Hassiubyte (HaB) (2²¹⁰)
• Meitnerbyte (MnB) (2²²⁰)
• Darmstadbyte (DrB) (2²³⁰)
• Roentbyte (RaB) (2²⁴⁰)
• Sophobyte (SoB) (2²⁵⁰)
• Coperbyte (CoB) (2²⁶⁰)
• Koentekbyte (KoB) (2²⁷⁰)
• Glossybyte (GsB) (2²⁸⁰)
• Snugbyte (SuB) (2²⁹⁰)
• Grandbyte (GrB) (2²⁹⁹)
• Doombyte (DmB) (2³⁰⁹)
• Godbyte (GdB) (2³¹⁹)
• Superbyte (SpB) (2³²⁹)
• Googolbyte (GgB) (2³³⁹)

Byte Chart

According to the International Electrotechnical Commission (IEC), who sets many computer standards, these charts show how bytes should be referred to.

People who refer to 1 kilobyte as 1,024 bytes, for example, are technically incorrect; 1,024 bytes should be referred to as 1 kibibyte, according to the IEC. However, using 1024 for kilo and 1048576 for mega, etc. was widely practiced before the IEC standards were set in 1998. There is some confusion and mixing of terms in the marketplace. Computer memory is still referred to in powers of 2, so 1KB of memory is 1024 bytes, whereas in computer data storage powers of 10 are used, so 1KB is 1000 bytes.

"kilo-" = 1,000

When using standard metric names like "kilo-", "mega-" and "giga-", they should follow the same measure that other metric measurements use, like kilometer (1 kilometer = 1,000 meters), or gigahertz (1 gigahertz = 1,000,000,000 hertz) for example.

Unit	Number	Short scale	Long scale	Scientific,E Notation/ Power of 10
Byte (B)	1	1 byte	1 byte	1*100,1E0 / 100
Kilobyte (KB)	1,000	1 thousand bytes	1 thousand bytes	1*103,1E3 / 103
Megabyte (MB)	1,000,000	1 million bytes	1 million bytes	1*106,1E6 / 106
Gigabyte (GB)	1,000,000,000	1 billion bytes	1 billion bytes	1*109,1E9 / 109
Terabyte (TB)	1,000,000,000,000	1 trillion bytes	1 trillion bytes	1*1012,1E12 / 1012
Petabyte (PB)	1,000,000,000,000,000	1 quadrillion bytes	1 quadrillion bytes	1*1015,1E15 / 1015
Exabyte (EB)	1,000,000,000,000,000,000	1 quintillion bytes	1 quintillion bytes	1*1018,1E18 / 1018
Zettabyte (ZB)	1,000,000,000,000,000,000,000	1 sextillion bytes	1 sextillion bytes	1*1021,1E21 / 1021
Yottabyte (YB)	1,000,000,000,000,000,000,000,000	1 septillion bytes	1 septillion bytes	1*1024,1E24 / 1024
Brontobyte (BB) (unofficial)	1,000,000,000,000,000,000,000,000,000	1 octillion bytes	1 octillion bytes	1*1027,1E27 / 1027
Geopbyte (GpB/GeB) (unofficial)	1,000,000,000,000,000,000,000,000,000,000	1 nonillion bytes	1 nonillion bytes	1*1030,1E30 / 1030
Saganbyte (SB) (unofficial)	1,000,000,000,000,000,000,000,000,000,000,000	1 Decillion bytes	1 Decillion bytes	1*1033,1E33 / 1033
Pijabyte (PjB) (unofficial)	1,000,000,000,000,000,000,000,000,000,000,000,000	1 Undecillion bytes	1 Undecillion bytes	1*1036,1E36 / 1036
Alphabyte (AB) (unofficial)	1,000,000,000,000,000,000,000,000,000,000,000,000,000	1 Duodecillion bytes	1 Duodecillion bytes	1*1039,1E39 / 1039
Pectrolbyte (PcB) (unofficial)	1,000,000,000,000,000,000,000,000,000,000,000,000,000,000	1 Tredecillion bytes	1 Tredecillion bytes	1*1042,1E42 / 1042
Bolgerbyte (BoB) (unofficial)	1,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000	1 Quattuordecillion bytes	1 Quattuordecillion bytes	1*1045,1E45 / 1045
Sambobyte (SaB) (unofficial)	1,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000	1 Quindecillion bytes	1 Quindecillion bytes	1*1048,1E48 / 1048
Quesabyte (QB) (unofficial)	1,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000	1 Sexdecillion bytes	1 Sexdecillion bytes	1*1051,1E51 / 1051
Kinsabyte (KiB) (unofficial)	1,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000	1 Septendecillion bytes	1 Septendecillion bytes	1*1054,1E54 / 1054
Rutherbyte (RB) (unofficial)	1,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000	1 Octodecillion bytes	1 Octodecillion bytes	1*1057,1E57 / 1057
Dubnibyte (DB) (unofficial)	1,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000	1 Novemdecillion bytes	1 Novemdecillion bytes	1*1060,1E60 / 1060
Hassiubyte (HaB) (unofficial)	1,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000	1 Vigintillion bytes	1 Vigintillion bytes	1*1063,1E63 / 1063
Meitnerbyte (MnB) (unofficial)	1,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000	1 Unvigintillion bytes	1 Unvigintillion bytes	1*1066,1E66 / 1066
Darmstadbyte (DrB) (unofficial)	1,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000	1 Duovigintillion bytes	1 Duovigintillion bytes	1*1069,1E3 / 1069
Roentbyte (RaB) (unofficial)	1,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000	1 Trevigintillion bytes	1 Trevigintillion bytes	1*1072,1E3 / 1072
Sophobyte (SoB) (unofficial)	1,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000	1 Quattuorvigintillion bytes	1 Quattuorvigintillion bytes	1*1075,1E3 / 1075
Coperbyte (CoB) (unofficial)	1,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000	1 Quinvigintillion bytes	1 Quinvigintillion bytes	1*1078,1E78 / 1078
Koentekbyte (KoB) (unofficial)	1,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000	1 Sexvigintillion bytes	1 Sexvigintillion bytes	1*1081,1E81 / 1081
Glossybyte (GsB) (unofficial)	1,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000	1 Septenvigintillion bytes	1 Septenvigintillion bytes	1*1084,1E84 / 1084
Snugbyte (SuB) (unofficial)	1,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000	1 Octovigintillion bytes	1 Octovigintillion bytes	1*1087,1E87 / 1087
Grandbyte (GrB) (unofficial)	1,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000	1 Nonvigintillion bytes	1 Nonvigintillion bytes	1*1090,1E90 / 1090
Doombyte (DmB) (unofficial)	1,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000	1 Trigintillion bytes	1 Trigintillion bytes	1*1093,1E93 / 1093
Godbyte (GdB) (unofficial)	1,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000	1 Untrigintillion bytes	1 Untrigintillion bytes	1*1096,1E96 / 1096
Superbyte (SpB) (unofficial)	1,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000	1 Duotrigintillion bytes	1 Duotrigintillion bytes	1*1099,1E99 / 1099
Googolbyte (GgB) (unofficial)	10,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000	1 Googol bytes	1 Googol bytes	1*10100,1E100 / 10100

"kibi-" = 1,024

Since computers are very complex digital devices that are based on the binary numeral system rather than the commonly-used decimal numeral system or binary coded decimal system, there are many situations where the standard metric system does not work well, particularly with memory sizes for a computer or storage device. If a memory or storage device uses a binary number for addresses, the number of different positions to be accessed (the size of the memory) can be expressed as a power of 2, rather than a power of 10.

Unit	Number	Maths
Byte (B)	1	20 bytes
Kibibyte (KiB)	1,024	210 bytes
Mebibyte (MiB)	1,048,576	220 bytes
Gibibyte (GiB)	1,073,741,824	230 bytes
Tebibyte (TiB)	1,099,511,627,776	240 bytes
Pebibyte (PiB)	1,125,899,906,842,624	250 bytes
Exbibyte (EiB)	1,152,921,504,606,846,976	260 bytes
Zebibyte (ZiB)	1,180,591,620,717,411,303,424	270 bytes
Yobibyte (YiB)	1,208,925,819,614,629,174,706,176	280 bytes
Bronbibyte (BiB) (unofficial)	1,237,940,039,285,380,274,899,124,224	290 bytes
Gebibyte (GeiB) (unofficial)	1,267,650,600,228,229,401,496,703,205,376	2100 bytes
Sagbibyte (SiB) (unofficial)	1,298,074,214,633,706,907,132,624,082,305,024	2110 bytes
Pijbibyte (PjiB) (unofficial)	1,329,227,995,784,915,872,903,807,060,280,344,576	2120 bytes
Alphbibyte (AiB) (unofficial)	1,361,129,467,683,753,853,853,498,429,727,072,845,824	2130 bytes
Pectbibyte (PciB) (unofficial)	1,393,796,574,908,163,946,345,982,392,040,522,594,123,776	2140 bytes
Bolgbibyte (BoiB) (unofficial)	1,427,247,692,705,959,881,058,285,969,449,495,136,382,746,624	2150 bytes
Sambibyte (SaiB) (unofficial)	1,461,501,637,330,902,918,203,684,832,716,283,019,655,932,542,976	2160 bytes
Quesbibyte (QiB) (unofficial)	1,496,577,676,626,844,588,240,573,268,701,473,812,127,674,924,007,424	2170 bytes
Kinsbibyte (KiiB) (unofficial)	1,532,495,540,865,888,858,358,347,027,150,309,183,618,739,122,183,602,176	2180 bytes
Ruthbibyte (RiB) (unofficial)	1,569,275,433,846,670,190,958,947,355,801,916,604,025,588,861,116,008,628,224	2190 bytes
Dubbibyte (DiB) (unofficial)	1,606,938,044,258,990,275,541,962,092,341,162,602,522,202,993,782,792,835,301,376	2200 bytes
Hassbibyte (HaiB) (unofficial)	1,645,504,557,321,206,042,154,969,182,557,350,504,982,735,865,633,579,863,348,609,024	2210 bytes
Meitbibyte (MniB) (unofficial)	1,684,996,666,696,914,987,166,688,442,938,726,917,102,321,526,408,785,780,068,975,640,576	2220 bytes
Darmbibyte (DriB) (unofficial)	1,725,436,586,697,640,946,858,688,965,569,256,363,112,777,243,042,596,638,790,631,055,949,824	2230 bytes
Roentbibyte (RaiB) (unofficial)	1,766,847,064,778,384,329,583,297,500,742,918,515,827,483,896,875,618,958,121,606,201,292,619,776	2240 bytes
Sophbibyte (SoiB) (unofficial)	1,809,251,394,333,065,553,493,296,640,760,748,560,207,343,510,400,633,813,116,524,750,123,642,650,624	2250 bytes
Copbibyte (CoiB) (unofficial)	1,852,673,427,797,059,126,777,135,760,139,006,525,652,319,754,650,249,024,631,321,344,126,610,074,238,976	2260 bytes
Koentbibyte (KoiB) (unofficial)	1,897,137,590,064,188,545,819,787,018,382,342,682,267,975,428,761,855,001,222,473,056,385,648,716,020,711,424	2270 bytes
Glossbibyte (GsiB) (unofficial)	1,942,668,892,225,729,070,919,461,906,823,518,906,642,406,839,052,139,521,251,812,409,738,904,285,205,208,498,176	2280 bytes
Snugbibyte (SuiB) (unofficial)	1,989,292,945,639,146,568,621,528,992,587,283,360,401,824,603,189,390,869,761,855,907,572,637,988,050,133,502,132,224	2290 bytes
Grandbibyte (GriB) (unofficial)	1,018,517,988,167,243,043,134,222,844,204,689,080,525,734,196,832,968,125,318,070,224,677,190,649,881,668,353,091,698,688	2299 bytes
Doombyte (DmiB) (unofficial)	1,042,962,419,883,256,876,169,444,192,465,601,618,458,351,817,556,959,360,325,703,910,069,443,225,478,828,393,565,899,456,512	2309 bytes
Godbibyte (GdiB) (unofficial)	1,067,993,517,960,455,041,197,510,853,084,776,057,301,352,261,178,326,384,973,520,803,911,109,862,890,320,275,011,481,043,468,288	2319 bytes
Supbibyte (SpiB) (unofficial)	1,093,625,362,391,505,962,186,251,113,558,810,682,676,584,715,446,606,218,212,885,303,204,976,499,599,687,961,611,756,588,511,526,912	2329 bytes
Googolbibyte (GgiB) (unofficial)	1,119,872,371,088,902,105,278,721,140,284,222,139,060,822,748,617,324,767,449,994,550,481,895,935,590,080,472,690,438,746,635,803,557,888	2339 bytes