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Physical unit
Unit name liter
Unit symbol , ,
Physical quantity (s) volume
Formula symbol
system Approved for use with the SI
In SI units
In CGS units

The (outside of Switzerland also: the) liter is a unit for the volume and is symbolized by the unit symbol , or or abbreviated as Ltr .

One liter corresponds to one cubic decimeter (dm³). A cube with an edge length of 10  cm therefore has a volume of one liter.

Although the liter does not belong to the International System of Units (SI), it is approved for use with the SI. The liter is a legal unit of measurement by national law .


The German unit name liter [ ˈliːtɐ , also: ˈlɪtɐ ] comes from French liter [from Middle French litron (a measure of measure), Middle Latin litra , Greek lítra = pound].

Basically, in the International System of Units (SI), the unit symbols are written in lower case, unless the name of the unit is derived from a person's proper name. In this case, the first letter of the character is capitalized. Accordingly, the unit symbol for the liter is a lowercase l , since the unit name liter was not derived from a proper name.

The uppercase L was exceptionally approved by the CGPM as an alternative unit symbol for the liter in order to avoid confusion between the letter l and the number 1 , which can occur in some fonts, and is more commonly used in English and French-speaking countries. ISO and IEC only use the original symbol l . IUPAC and DIN  1301-1 allow both spellings.

Occasionally, a lowercase l in cursive (ℓ) is used to distinguish the unit symbol from the number 1 or the capital letter I. The associated Unicode code point for the “ℓ” is U + 2113.

The unit name liter used to be neuter according to DIN 1301-1. However, this no longer coincided with common usage. The Duden, for example, only mentions the neuter form in second place. With DIN 1301-1: 2010-10 this definition was changed compared to DIN 1301-1: 2002-10; the unit name liter is now defined as male.


A cube with an edge length of 10 cm has a volume of one liter.

Common decimal parts and multiples of the liter are:

designation unit factor Different
Femtoliter fl 10 -15 0.001 pl a billiardth of a liter, corresponds to a cubic micrometer (1 μm³)
Picoliters pl 10 −12 0.001 nl a trillionth of a liter
Nanoliters nl 10 −9 0.001 µL a billionth of a liter
Microliters μl 10 −6 0.001 ml one millionth of a liter, corresponds to one cubic millimeter (1 mm³)
Milliliters ml 10 −3 0.1 cl one thousandth of a liter, corresponds to one cubic centimeter (1 cm³)
Centiliters cl 10 −2 0.1 dl a hundredth of a liter, a typical shot glass has a volume of 2 cl
deciliter dl 10 −1 0.1 l a tenth of a liter
liter l 10 0 1000 ml = 100 cl = 10 dl corresponds to one cubic decimeter (1 dm³), the size of a typical milk carton
Hectoliters St. 10 2 100 l one hundred liters, a typical unit in the beverage industry

Even larger quantities of liquids (especially water) are given in cubic meters . 1 m³ corresponds to 1000 liters. For example, the Rhine in Basel has an average discharge rate of 1040 m³ / s.


In 1793, the liter was introduced in France as the new Republican unit of measurement (in connection with the metric system ) and equated to a cubic decimeter.

In 1879, the CIPM adopted the French liter definition and prescribed the use of the l (lowercase letter l) as a symbol.

In 1901 the liter was redefined on the third CGPM to the volume that 1 kg of pure water has at the temperature of its highest density under normal pressure (1013.25 hPa ). The liter was about 1,000 028  dm³ (originally 1,000 027  dm³ specified for the conversion). Due to the new task for this unit of measurement, to couple mass and volume via a special measured variable of the water, pure water still had a density of 999.975 kg / m³ under these conditions, but now exactly 1,000 kg / l.

Later, the definition was set to the water temperature of 4 ° C, which is not the temperature of the highest water density (actually around 3.98 ° C). Thus, pure water again had a slightly lower maximum density than 1,000 kg / l.

In 1964 at the 12th CGPM the definition of 1793 was restored, since then a liter has been exactly one cubic decimeter again and water has a density of 0.999 as before 1901 975  kg / l.

In 1979, at the 16th CGPM, the alternative symbol L (capital letter L) was approved for the liter , at the same time the wish was expressed to keep only one of the two symbols (lower case or upper case) in the future. Most recently in 1990 it could only be determined that it was still too early to make a decision.

Web links

Wiktionary: Liter  - explanations of meanings, word origins, synonyms, translations

Individual evidence

  1. Duden: Liter
  2. Duden entry Abbreviations, abbreviations and standardized abbreviations
  3. ^ SI brochure: The International System of Units , Physikalisch-Technische Bundesanstalt: PTB-Mitteilungen 117 (2007), Issue 2 (PDF file; 1010 kB)
  4. enacted on the basis of EU Directive 80/181 / EEC in the states of the EU or the federal law on metrology in Switzerland
  5. a b Duden - The large dictionary of the German language . Bibliographisches Institut & FA Brockhaus AG, Mannheim 2000, ISBN 3-411-71001-2 .
  6. a b c Bureau international des poids et mesures (BIPM) : Le Système international d'unités (SI) , 9e édition 2019, [1]
  7. a b c d ISO 80000-1 : 2009, Quantities and units - Part 1: General, November 15, 2009
  8. a b c ISO 80000-3 : 2006, Quantities and units - Part 3: Space and time, March 1, 2006
  9. ER Cohen, T. Cvitaš, JG Frey, B. Holmstrom, K. Kuchitsu, R. Marquardt, I. Mills, F. Pavese, M. Quack, J. Stohner, HL Strauss, M. Takami, AJ Thor: Quantities , Units and Symbols in Physical Chemistry , IUPAC Green Book, 3rd Edition, 2nd Printing, IUPAC & RSC Publishing, Cambridge 2008
  10. a b DIN 1301-1: 2010-10 units - Part 1: Unit names, unit symbols, October 2010
  11. ^ Resolution of the 3rd meeting of the CGPM (1901) ( online , accessed March 1, 2020).
  12. ^ Resolution 6 of the 12th meeting of the CGPM (1964) ( online , accessed March 1, 2020).
  13. ^ Resolution 6 of the 16th meeting of the CGPM (1979) ( online , accessed March 1, 2020).