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 ἑκατόν hekatón, meaning "hundred". In 19th century English it was sometimes spelled "hecato", in line with a puristic opinion by Thomas Young.^[1][2] Its unit symbol as an SI prefix in the International System of Units (SI) is the lower case letter h.

Look up hecto- in Wiktionary, the free dictionary.

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 etto, 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).

• Metric prefix
• Numeral prefix