Femto-

This article describes the SI prefix. For the manga character, see Griffith (Berserk).

Femto- (symbol f) is a prefix in the metric system denoting a factor of 10⁻¹⁵ or 0.000000000000001. Adopted by the 11th Conférence Générale des Poids et Mesures, it was added in 1964 to the SI. It is derived from the Danish word femten, meaning "fifteen".

Example of use:

• a proton has a diameter of about 1.6 to 1.7 femtometres.

The femtometre shares the unit symbol (fm) with the older non-SI unit fermi, to which it is equivalent. The fermi, named in honour of Enrico Fermi, is often encountered in nuclear physics.

Metric prefixes

Prefix Symbol 1000m 10n Decimal Short scale Long scale Since 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 1960 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 1960 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

External links

• Bureau International des Poids et Mesures (BIPM)