Pico-

This article is about the SI prefix. For other uses, see Pico (disambiguation).

Pico (unit symbol p) is a unit prefix in the metric system denoting a factor of one trillionth in the short scale and one billionth in the long scale (0.000000000001); that is, 10⁻¹².

Derived from the Spanish word pico, (peak, beak, little bit), pico is one of the original twelve prefixes defined in 1960 when the International System of Units (SI) was established.

Atomic radii range from 28 picometers (pm) for helium to 260 pm for caesium. One picolight-year (ply) is about nine kilometers (six miles).

Carbon atom has radius of 77 picometers.

SI prefixes

Prefix		Base 10	Decimal	English word		Adoption	Etymology
Name	Symbol			Short scale	Long scale		Language	Derived word
yotta	Y	1024	1000000000000000000000000	septillion	quadrillion	1991	Greek	eight
zetta	Z	1021	1000000000000000000000	sextillion	trilliard	1991	Latin	seven
exa	E	1018	1000000000000000000	quintillion	trillion	1975	Greek	six
peta	P	1015	1000000000000000	quadrillion	billiard	1975	Greek	five
tera	T	1012	1000000000000	trillion	billion	1960	Greek	four, 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
femto	f	10−15	0.000000000000001	quadrillionth	billiardth	1964	Danish	fifteen, Fermi
atto	a	10−18	0.000000000000000001	quintillionth	trillionth	1964	Danish	eighteen
zepto	z	10−21	0.000000000000000000001	sextillionth	trilliardth	1991	Latin	seven
yocto	y	10−24	0.000000000000000000000001	septillionth	quadrillionth	1991	Greek	eight

See also

• RKM code