| prefix | symbol | value | value | ‘puter jargon usage | origin / plausible alternative |
| deca- | da |
101
|
101
|
[3], used to be “deka” |
Gk. ten “deka” |
| hecto- | h |
102
|
102
|
[3] | Gk. hundred “hekaton” |
| kilo- | k |
10001
|
103
|
note lower case “k” | Gk. thousand “chylioi” |
| myria- | ma, my |
104
|
104
|
[3], [4] | Gk. ten thousand “myrias” |
| hectokilo- | hk |
105
|
105
|
[4] | |
| mega- | M |
10002
|
106
|
Gk. large, great “megas” | |
| giga- | G |
10003
|
109
|
Gk. giant “gigas” | |
| tera- | T |
10004
|
1012
|
Gk. monster “teras” / Gk. four “tetra” | |
| peta- | P |
10005
|
1015
|
Gk. five “penta” / Gk. spread “petalos” | |
| exa- | E |
10006
|
1018
|
Gk. six hexa” / Gk. outside “exo” | |
| zetta- | Z |
10007
|
1021
|
L. ultimate letter z “zeta” | |
| yotta- | Y |
10008
|
1024
|
L. penultimate letter y “iota” | |
| harpi- | Hr |
10009
|
1027
|
[1] | Marx Bros. Harpo |
| grouchi- | Gc |
100010
|
1030
|
[1] | Marx Bros. Groucho |
| zeppi- | Zp |
100011
|
1033
|
[2] | Marx Bros. Zeppo |
| gummi- | Gm |
100012
|
1036
|
[2] | Marx Bros. Gummo |
| chici- | Ch |
100013
|
1039
|
[2] | Marx Bros. Chico |
| prefix | symb | value | value | computer jargon usage | origin / plausible alternative |
| deci- | d |
10-1
|
10-1
|
[3] | L. tenth “decimus” |
| centi- | c |
10-2
|
10-2
|
[3] | L. hundred, hundredth “centum” |
| milli- | m |
1000-1
|
10-3
|
seldom used in jargon | L. thousand “mille” |
| decimilli- | dm |
10-4
|
10-4
|
[4] | |
| centimilli- | cm |
10-5
|
10-5
|
[4] | |
| micro- | µ, u |
1000-2
|
10-6
|
[5] small or human-scale | L. small “mikros” |
| nano- | n |
1000-3
|
10-9
|
even smaller, used for RAM speed |
Gk. dwarf “nanos” |
| pico- | p |
1000-4
|
10-12
|
even smaller yet | It. tiny “piccolo” |
| femto- | f |
1000-5
|
10-15
|
not used in jargon – yet | O.N. fifteen “femten” |
| atto- | a |
1000-6
|
10-18
|
not used in jargon – yet | O.N. eighteen “atten” |
| zepto- | z |
1000-7
|
10-21
|
not used in jargon – yet | L. ultimate letter z “zeta” |
| yocto- | y |
1000-8
|
10-24
|
not used in jargon – yet | L. penultimate letter y “iota” |
| harpo- | hr |
1000-9
|
10-27
|
[1] | Marx Bros. Harpo |
| groucho- | gc |
1000-10
|
10-30
|
[1] | Marx Bros. Groucho |
| zeppo- | zp |
1000-11
|
10-33
|
[2] | Marx Bros. Zeppo |
| gummo- | gm |
1000-12
|
10-36
|
[2] | Marx Bros. Gummo |
| chico- | ch |
1000-13
|
1039
|
[2] | Marx Bros. Chico |
| prefix | symb | value | value | numerical value |
origin / plausible alternative |
| kilo- | K |
10241
|
210
|
1,024
|
binary usage, common in computer science |
| kibi- | Ki |
10241
|
210
|
1,024
|
IEEE proposal |
| mebi- | Mi |
10242
|
220
|
1,048,576
|
IEEE proposal |
| gibi- | Gi |
10243
|
230
|
1,073,741,824
|
IEEE proposal |
| tebi- | Ti |
10244
|
240
|
1,099,511,627,776
|
IEEE proposal |
| pebi- | Pi |
10245
|
250
|
1,125,899,906,842,624
|
IEEE proposal, by extension |
| exbi- | Ei |
10246
|
260
|
1,152,921,504,606,846,976
|
IEEE proposal, by extension |
| zebi | Zi |
10247
|
270
|
1,180,591,620,717,411,303,424
|
IEEE proposal, by extension |
| yobi- | Yi |
10248
|
280
|
1,208,925,819,614,629,174,706,176
|
IEEE proposal, by extension |
| [1] Not SI approved, Morgan Burke [1993] extension, Usenet approved. | |
| [2] Not SI approved, Jargon extension of the Burke extension. | |
| [3] Not SI approved, but in some common usage. | |
| [4] Rarely used, not SI approved. Elicits head-scratching and laughs. | |
| [5] The Greek mu µ is the highly preferred prefix. | |
| NOTE regarding the status of the IEEE proposal: the Comite Consultatif des Unites decided 1995/1996 not to pursue the mebibyte and related units further at that time. |
Computer jargon examples:
| attoparsec (approximately = 3.1cm) | |
| microfortnight (= 1.2096 sec) |