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 10¹² or 1000000000000 (one trillion short scale; one billion long scale). It has the symbol T. Tera is derived from Greek word τέρας 'teras', meaning "monster". The prefix tera- was confirmed for use in the 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, tebibit, terabyte and tebibyte, units used in data storage.
• 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.

SI prefixes

Prefix Base 1000 Base 10 Decimal English word Adoption 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 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 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