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Nano (symbol n) is a unit prefix meaning "one billionth". Used primarily with the metric system, this prefix denotes a factor of 10−9 or 0.000000001. It is frequently encountered in science and electronics for prefixing units of time and length.

  • One nanometer is about the length that a fingernail grows in one second.
  • Three gold atoms lined up are about one nanometer long.
  • If a toy marble were scaled down to one nanometer wide, Earth would scale to about 1 meter (3.3 ft) wide.[1]
  • One nanosecond is about the time required for light to travel 30 cm in air, or 20 cm in an optical fiber.

The prefix derives from the Greek νᾶνος (Latin nanus), meaning "dwarf". The General Conference on Weights and Measures (CGPM) officially endorsed the usage of nano as a standard prefix in 1960.

When used as a prefix for something other than a unit of measure (as for example in words like "nanoscience"), nano refers to nanotechnology, or means "on a scale of nanometres".

Prefix Base 10 Decimal English word Adoption[nb 1] Etymology
Name Symbol Short scale Long scale Language Source word
yotta Y 1024 1000000000000000000000000 septillion quadrillion 1991 Latin eight[nb 2]
zetta Z 1021 1000000000000000000000 sextillion trilliard 1991 Latin seven[nb 2]
exa E 1018 1000000000000000000 quintillion trillion 1975 Greek six
peta P 1015 1000000000000000 quadrillion billiard 1975 Greek five[nb 2]
tera T 1012 1000000000000 trillion billion 1960 Greek four,[nb 2] monster
giga G 109 1000000000 billion milliard 1960 Greek giant
mega M 106 1000000 million 1873 Greek great
kilo k 103 1000 thousand 1795 Greek thousand
hecto h 102 100 hundred 1795 Greek hundred
deca da 101 10 ten 1795 Greek ten
100 1 one
deci d 10−1 0.1 tenth 1795 Latin ten
centi c 10−2 0.01 hundredth 1795 Latin hundred
milli m 10−3 0.001 thousandth 1795 Latin thousand
micro μ 10−6 0.000001 millionth 1873 Greek small
nano n 10−9 0.000000001 billionth milliardth 1960 Greek dwarf
pico p 10−12 0.000000000001 trillionth billionth 1960 Spanish peak, a little bit
femto f 10−15 0.000000000000001 quadrillionth billiardth 1964 Danish fifteen, Fermi[nb 3]
atto a 10−18 0.000000000000000001 quintillionth trillionth 1964 Danish eighteen
zepto z 10−21 0.000000000000000000001 sextillionth trilliardth 1991 Latin seven[nb 2]
yocto y 10−24 0.000000000000000000000001 septillionth quadrillionth 1991 Latin eight[nb 2]
  1. ^ Prefixes adopted before 1960 already existed before SI. The introduction of the CGS system was in 1873.
  2. ^ a b c d e f Part of the beginning of the prefix was modified from the word it was derived from, ex: "peta" (prefix) vs "penta" (source word).
  3. ^ The fermi was introduced earlier with the symbol "fm", which prompted the reinterpretation of the "f" as a prefix to "m", with femto being derived from the Danish word femten due to its similarity.

See also[edit]


  1. ^ "Size of the Nanoscale". National Nanotechnology Initiative. Retrieved 2020-05-14.