Look up pico- in Wiktionary, the free dictionary. |
Pico- (symbol p) is a unit prefix in the metric system denoting one trillionth, a factor of 10−12 (0.000000000001).
Derived from the Spanish pico, meaning peak, beak, bit,[1] this was one of the original 12 prefixes defined in 1960 when the International System of Units was established.[2]
The radius of atoms range from 25 picometers (hydrogen) to 260 picometers (caesium). One picolight-year is about nine kilometers (six miles).
|
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Prefix
|
Base 1000
|
Base 10
|
Decimal
|
English word
|
Adoption[nb 1] |
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Name
|
Symbol
|
Short scale
|
Long scale
|
---|
yotta
|
Y
|
10008 |
1024
|
1000000000000000000000000
|
septillion
|
quadrillion
|
1991
| zetta
|
Z
|
10007 |
1021
|
1000000000000000000000
|
sextillion
|
trilliard
|
1991
| exa
|
E
|
10006 |
1018
|
1000000000000000000
|
quintillion
|
trillion
|
1975
| peta
|
P
|
10005 |
1015
|
1000000000000000
|
quadrillion
|
billiard (Proposed)
|
1975
| tera
|
T
|
10004 |
1012
|
1000000000000
|
trillion
|
billion
|
1960
| giga
|
G
|
10003 |
109
|
1000000000
|
billion
|
milliard
|
1960
| mega
|
M
|
10002 |
106
|
1000000
|
million
|
1873
| kilo
|
k
|
10001 |
103
|
1000
|
thousand
|
1795
| hecto
|
h
|
10002/3 |
102
|
100
|
hundred
|
1795
| deca
|
da
|
10001/3 |
101
|
10
|
ten
|
1795
|
|
10000 |
100
|
1
|
one
|
–
| deci
|
d
|
1000−1/3 |
10−1
|
0.1
|
tenth
|
1795
| centi
|
c
|
1000−2/3
|
10−2
|
0.01
|
hundredth
|
1795
| milli
|
m
|
1000−1 |
10−3
|
0.001
|
thousandth
|
1795
| micro
|
μ
|
1000−2 |
10−6
|
0.000001
|
millionth
|
1873
| nano
|
n
|
1000−3 |
10−9
|
0.000000001
|
billionth
|
milliardth
|
1960
| pico
|
p
|
1000−4 |
10−12
|
0.000000000001
|
trillionth
|
billionth
|
1960
| femto
|
f
|
1000−5 |
10−15
|
0.000000000000001
|
quadrillionth
|
billiardth (Proposed)
|
1964
| atto
|
a
|
1000−6 |
10−18
|
0.000000000000000001
|
quintillionth
|
trillionth
|
1964
| zepto
|
z
|
1000−7 |
10−21
|
0.000000000000000000001
|
sextillionth
|
trilliardth
|
1991
| yocto
|
y
|
1000−8 |
10−24
|
0.000000000000000000000001
|
septillionth
|
quadrillionth
|
1991
|
|
|
- ^ Prefixes adopted before 1960 already existed before SI. 1873 was the introduction of the CGS system.