Tera-

This article is about the SI prefix. For other uses, see Tera.

Tera is a unit prefix in the metric system denoting multiplication by one trillion, or 10¹² or 1000000000000 (one trillion short scale; one billion long scale). It has the symbol T. Tera is derived from the Greek word τέρας teras, meaning "monster"; also it resembles tetra, meaning "four" but with the middle letter removed as it is the fourth power of 1000. The unit prefix was confirmed for use in the International System of Units (SI) in 1960.

Examples of its use:

• terahertz radiation: electromagnetic waves within the band of frequencies from 0.3 to 3 THz. Visible light is around 500 THz.
• terabit and terabyte, units used in data storage. Tebi-, or 2⁴⁰ is the closest binary prefix being ≈9.95% greater than 10¹².
• teragram: equal to 10⁹ kg. The Great Pyramid of Giza has a mass of about 6 Tg.
• terasecond: approximately 31,558 years
• teralitre: equal to 10⁹ m³. Lake Zurich contains about 4 TL of water.
• terawatt: used to measure total human energy consumption. In 2010 it was 16 TW (TJ/s).
• terametre: (= 1,000,000,000 km): Light travels 1.079 Tm in one hour.
• terajoule: equal to 10¹² J of energy, approximately 1/4 kiloton of TNT.

SI prefixes

Prefix		Base 10	Decimal	English word		Adoption
Name	Symbol			Short scale	Long scale
yotta	Y	1024	1000000000000000000000000	septillion	quadrillion	1991
zetta	Z	1021	1000000000000000000000	sextillion	trilliard	1991
exa	E	1018	1000000000000000000	quintillion	trillion	1975
peta	P	1015	1000000000000000	quadrillion	billiard	1975
tera	T	1012	1000000000000	trillion	billion	1960
giga	G	109	1000000000	billion	milliard	1960
mega	M	106	1000000	million		1873
kilo	k	103	1000	thousand		1795
hecto	h	102	100	hundred		1795
deca	da	101	10	ten		1795
		100	1	one		–
deci	d	10−1	0.1	tenth		1795
centi	c	10−2	0.01	hundredth		1795
milli	m	10−3	0.001	thousandth		1795
micro	μ	10−6	0.000001	millionth		1873
nano	n	10−9	0.000000001	billionth	milliardth	1960
pico	p	10−12	0.000000000001	trillionth	billionth	1960
femto	f	10−15	0.000000000000001	quadrillionth	billiardth	1964
atto	a	10−18	0.000000000000000001	quintillionth	trillionth	1964
zepto	z	10−21	0.000000000000000000001	sextillionth	trilliardth	1991
yocto	y	10−24	0.000000000000000000000001	septillionth	quadrillionth	1991

See also

• RKM code