Numeral, Metric and Binary Prefixes

Uni, Bi, Kilo, Mibi etc.



Small Quantity Prefixes

Quantity Common Prefixes IUPAC Standard (Chemical Names)1
Semi-, Demi-, Hemi- N/A
1 Uni-, Mono- Mono-, hen-
2 Bi-, Di- Di-, do-
3 Tri- Tri
4 Quad-, Tetra- Tetra-
5 Penta- Penta-
6 Sex-, Hex- Hexa-
7 Sept-, Hept- Hepta-
8 Oct- Octa-
9 Nov-, Non- Nona-
10 Dec- Deca-
11 Undec-, Hendec-  
12 Duodec-, Dodec-  
13 Tredec-, Tridec-  
20 Icosa- Icosa-
100 Centi-, Hecta- Hecta-
1000 Kilo-, Kilia-
Few Pauci-, Oligo- N/A, Oligo- sometimes used
Many Multi-, Pluri-, Poly- N/A, Poly- sometimes used
All Omni- N/A

IUPAC Names 1

For higher multiples of 10, 100 and 1000:

  • 30, 40, 50 etc: Add -conta- (tetraconta-, pentaconta-)
  • 300, 400, 500 etc: Add -cta- (tricta-, tetracta-)
  • 2000, 3000 etc: Add -lia- (hexalia-, hexalia-)

To build numbers, join prefixes for each digit (replace mono- with hen- and di- with do-)

For complex features, -kis- is added:

  • 5 = pentakis-
  • 421 = henicosatetractakis-
  • Note mono- remains unchanged, di- becomes bis- and tri- becomes tris-

Metric and Binary Prefixes

Metric Prefix2 Symbol Factor Factor Symbol Metric Prefix
Yotta Y y Yocto
Zetta Z z Zepto
Exa E a Atto
Peta P f Femto
Tera T p Pico
Giga G n Nano
Mega M µ Micro
Kilo k m Milli
Hecto h c Centi
Deca da d Deci

When used to denote a number of bits/bytes (kilobyte, megabit, etc.), there is some ambiguity as whether these units refer to a multiple of , as above, or a multiple of . The IEC defines the following Binary Prefixes in an attempt to alleviate this issue, although adoption is ultimately implementation dependent.

Binary Prefix3 Symbol Factor
Yobi Yi
Zebi Zi
Exbi Ei
Pebi Pi
Tebi Ti
Gibi Gi
Mebi Mi
Kibi Ki