International System of Units (SI) SI Prefixes Multiples 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 deka da Submultiplies Factor Name Symbol 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 Note: The kilogram is the only SI unit with a prefix as part of its name and symbol. Because multiple prefixes are not allowed, the kilogram and prefix names are used with the unit name gram and the prefix symbols are used with the unit symbol g. Other than in this case, any SI prefix may be used with any SI unit, including the degree Celsius and its symbol °C. Example: 10–6 kg = 1 mg (one milligram), but not 10–6 kg = 1 μkg (one microkilogram) Source: National Institute of Standards and Technology (NIST)
