Deci- (symbol d) is a decimal unit prefix in the metric system denoting a factor of one tenth. Proposed in 1793,[1] and adopted in 1795, the prefix comes from the Latin decimus, meaning "tenth". Since 1960, the prefix is part of the International System of Units (SI).[2][3]

A frequent use of the prefix is in the unit deciliter (dl), common in food recipes; many European homes have a deciliter measure for flour, water, etc. A common measure in engineering is the unit decibel for measuring ratios of power and root-power quantities, such as sound level and electrical amplification.

Example
• The diameter of a compact disc is about 12 centimetres or 1.2 decimetres.[4]
[nb 1]
Name Symbol
quetta Q 1030 1000000000000000000000000000000 2022[5]
ronna R 1027 1000000000000000000000000000
yotta Y 1024 1000000000000000000000000 1991
zetta Z 1021 1000000000000000000000
exa E 1018 1000000000000000000 1975[6]
peta P 1015 1000000000000000
tera T 1012 1000000000000 1960
giga G 109 1000000000
mega M 106 1000000 1873
kilo k 103 1000 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 0.000001 1873
nano n 10−9 0.000000001 1960
pico p 10−12 0.000000000001
femto f 10−15 0.000000000000001 1964
atto a 10−18 0.000000000000000001
zepto z 10−21 0.000000000000000000001 1991
yocto y 10−24 0.000000000000000000000001
ronto r 10−27 0.000000000000000000000000001 2022[5]
quecto q 10−30 0.000000000000000000000000000001
Notes
1. ^ Prefixes adopted before 1960 already existed before SI. The introduction of the CGS system was in 1873.

## References

1. ^ Commission temporaire de Poids & Mesures rêpublicaines, En exécution des Décrets de la Convention Nationale (1793). Instruction abrégée sur les mesures déduites de la grandeur de la Terre; uniformes pour toute la Rêpublique, et sur les Calculs relatifs à leur division décimale (in French) (Edition originale ed.). Paris, France: De l´imprimerie nationale exécutive du Louvre. Retrieved 2015-10-09.
2. ^ The International System of Units (Si): The Metric System. DIANE Publishing. 1992. p. 30. ISBN 9780941375740.
3. ^ "Resolution 12 of the 11th CGPM". BIPM. 1960. Archived from the original on 2020-04-08. Retrieved 2020-05-14.
4. ^ "Universcale: From the nanoworld to the universe — The worlds we measure using our infinite yardstick". Nikon. 2013. Archived from the original on 2017-02-08. Retrieved 2017-02-08.
5. ^ a b "On the extension of the range of SI prefixes". 18 November 2022. Retrieved 5 February 2023.
6. ^ "Metric (SI) Prefixes". NIST.