Hecto-

Template:Short description Hecto (symbol: h) is a decimal unit prefix in the metric system denoting a factor of one hundred. It was adopted as a multiplier in 1795, and comes from the Greek , meaning "hundred". In 19th century English it was sometimes spelled "hecato", in line with a puristic opinion by Thomas Young. Its unit symbol as an SI prefix in the International System of Units (SI) is the lower case letter h.

The prefix is rarely used in general, but has certain specific applications:

• hectopascal (hPa), in meteorology, for atmospheric pressure, the modern equivalent of the traditional millibar.
• hectolitre (hl or hL), in agriculture, for liquids (notably milk and alcoholic beverages) and bulk commodities (e.g., grain).
• hectogram (hg), in agronomy, for quantities of animal feed (hectogram/animal) and for measures of agricultural productivity (hectogram/hectare); also used in Italy abbreviated as , and in Canada, New Zealand and Sweden simply as 100 g, for retail sale of cold cuts and meat.
• hectometre (hm), in radio astronomy, occasionally used to indicate a radio band by wavelength
• In surveying, a square hectometre is called a hectare (ha, or 100 ares = 1 hm² = 10,000 m²).

See also

• Metric prefix
• Numeral prefix

References

SI prefixes

Prefix		Base 10	Decimal	Adoption
Name	Symbol
quetta	Q	1030		2022
ronna	R	1027
yotta	Y	1024		1991
zetta	Z	1021
exa	E	1018		1975
peta	P	1015
tera	T	1012		1960
giga	G	109
mega	M	106		1873
kilo	k	103		1795
hecto	h	102	100
deca	da	101	10
—	—	100	1	—
deci	d	10−1	0.1	1795
centi	c	10−2	0.01
milli	m	10−3	0.001
micro	μ	10−6		1873
nano	n	10−9		1960
pico	p	10−12
femto	f	10−15		1964
atto	a	10−18
zepto	z	10−21		1991
yocto	y	10−24
ronto	r	10−27		2022
quecto	q	10−30
Notes