SI prefixes

Kilo is a unit prefix in the metric system of measurement, denoting multiplication by one thousand (103). The International System of Units reserves the lowercase symbol k.

Milli (symbol m) is a unit prefix in the metric system denoting a factor of one thousandth (10−3). Proposed in 1793, and adopted in 1795, the prefix comes from the Latin , meaning one thousand (the Latin plural is ). Since 1960, the prefix is part of the International System of Units (SI).

Nano (symbol n) is a unit prefix meaning one billionth. Used primarily with the metric system, this prefix denotes a factor of 10−9 or . It is frequently encountered in science and electronics for prefixing units of time and length.

Micro (Greek letter μ, mu, non-italic) is a unit prefix in the metric system denoting a factor of one millionth (10−6). It comes from the Greek word (), meaning "small".

thumb|alt=Laptop-hard-drive-exposed|Laptop hard drive, with its platter exposed. Giga- ( or ) is a unit prefix in the metric system denoting a factor of a short-scale billion or long-scale milliard (109 or 1,000,000,000). It has the symbol G.

Mega is a unit prefix in metric systems of units denoting a factor of one million (106 or 1000000 (number)|). It has the unit symbol M. It was confirmed for use in the International System of Units (SI) in 1960. Mega comes from .

Centi (symbol c) is a unit prefix in the metric system denoting a factor of one hundredth. Proposed in 1793, and adopted in 1795, the prefix comes from the Latin , meaning "hundred" (cf. century, cent, percent, centennial). Since 1960, the prefix is part of the International System of Units (SI). It is mainly used in combination with the unit metre to form centimetre, a common unit of length.

Tera- (; symbol T) is a metric prefix denoting a factor of a short-scale trillion or long-scale billion (1012 or 1,000,000,000,000|). It was adopted in the International System of Units (SI) in 1960. The prefix is derived from the Greek word (téras), meaning "monster".

thumb|250px|French 1 decime coin, equal to of a franc. First Republic. Deci (symbol d) is a decimal unit prefix in the metric system denoting a factor of one tenth. Proposed in 1793, and adopted in 1795, the prefix comes from the Latin , meaning "tenth". Since 1960, the prefix is part of the International System of Units (SI).

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.

Deca (and dec; sometimes deka) is a common English-language numeral prefix derived from the Late Latin ("(set of) ten"), from Ancient Greek , from (déka, "ten"). It is used in many words.

REDIRECT Metric prefix#List of SI prefixes