Femto-

This redirect is about the SI prefix. For the manga character, see Griffith (Berserk).

Femto- (symbol f) is a unit prefix in the metric system denoting a factor of 10⁻¹⁵ or 0.000000000000001. Adopted by the 11th General Conference on Weights and Measures, it was added in 1964 to the SI. It is derived from the Danish word [femten] Error: {{Lang}}: text has italic markup (help), meaning "fifteen".

Examples of use:

• The HIV-1 virus weighs about 1 x 10⁻¹⁸ kg or 1 fg. Orders of magnitude (mass)
• a proton has a diameter of about 1.6 to 1.7 femtometres.
• More examples available.

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 in everyday use

Prefix	Symbol	Factor	Power
tera	T	1000000000000	1012
giga	G	1000000000	109
mega	M	1000000	106
kilo	k	1000	103
hecto	h	100	102
deca	da	10	101
(none)	(none)	1	100
deci	d	0.1	10−1
centi	c	0.01	10−2
milli	m	0.001	10−3
micro	μ	0.000001	10−6
nano	n	0.000000001	10−9
pico	p	0.000000000001	10−12

External links

• Bureau International des Poids et Mesures (BIPM)