Home | Map of the site | Contact us  
 
 
   
SI prefixes
Version française
Summary
SI base units
SI derived units
SI brochure
Brief history of the SI
SI prefixes
Search the SI brochure
Unit conversions
Linking SI base units to fundamental and atomic constants
Related articles
Rules for using SI prefixes
Prefixes for binary multiples adopted by the IEC
Direct access

SI brochure, section 3.1


The 11th CGPM (1960, Resolution 12) adopted a series of prefixes and prefix symbols to form the names and symbols of the decimal multiples and submultiples of SI units ranging from 1012 to 10–12. Prefixes for 10–15 and 10–18 were added by the 12th CGPM (1964, Resolution 8), for 1015 and 1018 by the 15th CGPM (1975, Resolution 10), and for 1021, 1024, 10–21 and 10–24 by the 19th CGPM (1991, Resolution 4). Table 5 lists all approved prefixes and symbols.


These SI prefixes refer strictly to powers of 10. They should not be used to indicate powers of 2 (for example, one kilobit represents 1000 bits and not 1024 bits).
Table 5. SI prefixes

Factor Name Symbol
Factor Name Symbol
1024 yotta Y
1021 zetta Z
1018 exa E
1015 peta P
1012 tera T
109 giga G
106 mega M
103 kilo k
102 hecto h
101 deca da
10–1 deci d
10–2 centi c
10–3 milli m
10–6 micro µ
10–9 nano n
10–12 pico p
10–15 femto f
10–18 atto a
10–21 zepto z
10–24 yocto y


Related articles

Rules for using SI prefixes
Prefixes for binary multiples adopted by the IEC