Как пишутся литры сокращенно

From Wikipedia, the free encyclopedia

This article is about a common unit of volume. For the plant commonly known as litre, see Lithraea caustica.

«ltr.» redirects here. For letter, see Letter.

litre
One litre is the volume of a cube with 10 cm sides.
General information
Unit system	Non-SI unit accepted for use with SI
Unit of	volume
Symbol	L or l (or ℓ)[1]
Named after	litron
Conversions
1 L in …	… is equal to …
SI base unit	10−3 m3
U.S. customary	≈ 0.264 gallon

The litre (international spelling) or liter (American English spelling) (SI symbols L and l,^[1] other symbol used: ℓ) is a metric unit of volume. It is equal to 1 cubic decimetre (dm³), 1000 cubic centimetres (cm³) or 0.001 cubic metre (m³). A cubic decimetre (or litre) occupies a volume of 10 cm × 10 cm × 10 cm (see figure) and is thus equal to one-thousandth of a cubic metre.

The original French metric system used the litre as a base unit. The word litre is derived from an older French unit, the litron, whose name came from Byzantine Greek—where it was a unit of weight, not volume^[2]—via Late Medieval Latin, and which equalled approximately 0.831 litres. The litre was also used in several subsequent versions of the metric system and is accepted for use with the SI,^[3] although not an SI unit—the SI unit of volume is the cubic metre (m³). The spelling used by the International Bureau of Weights and Measures is «litre»,^[3] a spelling which is shared by most English-speaking countries. The spelling «liter» is predominantly used in American English.^[a]

One litre of liquid water has a mass of almost exactly one kilogramme, because the kilogramme was originally defined in 1795 as the mass of one cubic decimetre of water at the temperature of melting ice (0 °C).^[4] Subsequent redefinitions of the metre and kilogramme mean that this relationship is no longer exact.^[5]

Definition[edit]

A litre is a cubic decimetre, which is the volume of a cube 10 centimetres × 10 centimetres × 10 centimetres (1 L ≡ 1 dm³ ≡ 1000 cm³). Hence 1 L ≡ 0.001 m³ ≡ 1000 cm³; and 1 m³ (i.e. a cubic metre, which is the SI unit for volume) is exactly 1000 L.

From 1901 to 1964, the litre was defined as the volume of one kilogram of pure water at maximum density (+4 °C) and standard pressure. The kilogram was in turn specified as the mass of the International Prototype of the Kilogram (a specific platinum/iridium cylinder) and was intended to be of the same mass as the 1 litre of water referred to above. It was subsequently discovered that the cylinder was around 28 parts per million too large and thus, during this time, a litre was about 1.000028 dm³. Additionally, the mass–volume relationship of water (as with any fluid) depends on temperature, pressure, purity and isotopic uniformity. In 1964, the definition relating the litre to mass was superseded by the current one. Although the litre is not an SI unit, it is accepted by the CGPM (the standards body that defines the SI) for use with the SI. CGPM defines the litre and its acceptable symbols.

A litre is equal in volume to the millistere, an obsolete non-SI metric unit formerly customarily used for dry measure.

Explanation[edit]

Litres are most commonly used for items (such as fluids and solids that can be poured) which are measured by the capacity or size of their container, whereas cubic metres (and derived units) are most commonly used for items measured either by their dimensions or their displacements. The litre is often also used in some calculated measurements, such as density (kg/L), allowing an easy comparison with the density of water.

One litre of water has a mass of almost exactly one kilogram when measured at its maximal density, which occurs at about 4 °C. It follows, therefore, that 1000th of a litre, known as one millilitre (1 mL), of water has a mass of about 1 g; 1000 litres of water has a mass of about 1000 kg (1 tonne or megagram). This relationship holds because the gram was originally defined as the mass of 1 mL of water; however, this definition was abandoned in 1799 because the density of water changes with temperature and, very slightly, with pressure.

It is now known that the density of water also depends on the isotopic ratios of the oxygen and hydrogen atoms in a particular sample. Modern measurements of Vienna Standard Mean Ocean Water, which is pure distilled water with an isotopic composition representative of the average of the world’s oceans, show that it has a density of 0.999975±0.000001 kg/L at its point of maximum density (3.984 °C) under one standard atmosphere (101.325 kPa) of pressure.^[6]

SI prefixes applied to the litre[edit]

The litre, though not an official SI unit, may be used with SI prefixes. The most commonly used derived unit is the millilitre, defined as one-thousandth of a litre, and also often referred to by the SI derived unit name «cubic centimetre». It is a commonly used measure, especially in medicine, cooking and automotive engineering. Other units may be found in the table below, where the more often used terms are in bold. However, some authorities advise against some of them; for example, in the United States, NIST advocates using the millilitre or litre instead of the centilitre.^[7] There are two international standard symbols for the litre: L and l. In the United States the former is preferred because of the risk that (in some fonts) the letter l and the digit 1 may be confused.^[8]

Multiple	Name	Symbols	Equivalent volume
10−30 L	quectolitre	ql	qL	103 pm3	thousand cubic picometres
10−27 L	rontolitre	rl	rL	106 pm3	million cubic picometres
10−24 L	yoctolitre	yl	yL	nm3	cubic nanometre
10−21 L	zeptolitre	zl	zL	103 nm3	thousand cubic nanometres
10−18 L	attolitre	al	aL	106 nm3	million cubic nanometres
10−15 L	femtolitre	fl	fL	μm3	cubic micrometre
10−12 L	picolitre	pl	pL	103 μm3	thousand cubic micrometres
10−9 L	nanolitre	nl	nL	106 μm3	million cubic micrometres
10−6 L	microlitre	μl	μL	mm3	cubic millimetre
10−3 L	millilitre	ml	mL	cm3	cubic centimetre
10−2 L	centilitre	cl	cL	101 cm3	ten cubic centimetres
10−1 L	decilitre	dl	dL	102 cm3	hundred cubic centimetres
100 L	litre	l	L	dm3	cubic decimetre
101 L	decalitre	dal	daL	101 dm3	ten cubic decimetres
102 L	hectolitre	hl	hL	102 dm3	hundred cubic decimetres
103 L	kilolitre	kl	kL	m3	cubic metre
106 L	megalitre	Ml	ML	dam3	cubic decametre, 1 million litres
109 L	gigalitre	Gl	GL	hm3	cubic hectometre
1012 L	teralitre	Tl	TL	km3	cubic kilometre
1015 L	petalitre	Pl	PL	103 km3	thousand cubic kilometres
1018 L	exalitre	El	EL	106 km3	million cubic kilometres
1021 L	zettalitre	Zl	ZL	Mm3	cubic megametre
1024 L	yottalitre	Yl	YL	103 Mm3	thousand cubic megametres
1027 L	ronnalitre	Rl	RL	106 Mm3	million cubic megametres
1030 L	quettalitre	Ql	QL	Gm3	cubic gigametre

Non-metric conversions[edit]

Approx. value of 1 litre in non-metric units		Non-metric unit	Equivalent in litres
≈ 0.87987699	Imperial quart	1 Imperial quart	≡ 1.1365225 L
≈ 1.056688	U.S. quarts	1 U.S. quart	≡ 0.946352946 L
≈ 1.75975399	Imperial pints	1 Imperial pint	≡ 0.56826125 L
≈ 2.11337641	U.S. pints	1 U.S. pint	≡ 0.473176473 L
≈ 0.21996925	Imperial gallon	1 Imperial gallon	≡ 4.54609 L
≈ 0.2641720523	U.S. gallon	1 U.S. gallon	≡ 3.785411784 L
≈ 0.0353146667	cubic foot	1 cubic foot	≡ 28.316846592 L
≈ 61.023744	cubic inches	1 cubic inch	≡ 0.016387064 L
≈ 35.19508	Imperial fluid ounces	1 Imperial fluid ounce	≡ 28.4130625 mL
≈ 33.814023	U.S. fluid ounces	1 U.S. fluid ounce	≡ 29.5735295625 mL

See also Imperial units and US customary units.

Rough conversions[edit]

One litre is slightly larger than a US liquid quart and slightly less than an imperial quart or one US dry quart. A mnemonic for its volume relative to an imperial pint is «a litre of water’s a pint and three-quarters»; this is very close, as a litre is actually 1.75975399 pints.

A cubic foot has an exact volume of 28.316846592 litres.

Symbol[edit]

Originally, the only symbol for the litre was l (lowercase letter L), following the SI convention that only those unit symbols that abbreviate the name of a person start with a capital letter. In many English-speaking countries, however, the most common shape of a handwritten Arabic digit 1 is just a vertical stroke; that is, it lacks the upstroke added in many other cultures. Therefore, the digit «1» may easily be confused with the letter «l». In some computer typefaces, the two characters are barely distinguishable. As a result, L (uppercase letter L) was adopted by the CIPM as an alternative symbol for litre in 1979.^[9] The United States National Institute of Standards and Technology now recommends the use of the uppercase letter L,^[10] a practice that is also widely followed in Canada and Australia. In these countries, the symbol L is also used with prefixes, as in mL and μL, instead of the traditional ml and μl used in Europe. In the UK and Ireland, as well as the rest of Europe, lowercase l is used with prefixes, though whole litres are often written in full (so, «750 ml» on a wine bottle, but often «1 litre» on a juice carton). In 1990, the International Committee for Weights and Measures stated that it was too early to choose a single symbol for the litre.^[11]

Script l [edit]

Prior to 1979, the symbol ℓ came into common use in some countries;^{[citation needed]} for example, it was recommended by South African Bureau of Standards publication M33 and Canada in the 1970s. This symbol can still be encountered occasionally in some English-speaking and European countries like Germany, and its use is ubiquitous in Japan and South Korea.

Fonts covering the CJK characters usually include not only the script small ℓ but also four precomposed characters: ㎕, ㎖, ㎗, and ㎘ for the microlitre, millilitre, decilitre and kilolitre to allow correct rendering for vertically written scripts. These have Unicode equivalents for compatibility, which are not recommended for use with new documents:^[12]

• U+2113 ℓ SCRIPT SMALL L
• U+3395 ㎕ SQUARE MU L
• U+3396 ㎖ SQUARE ML
• U+3397 ㎗ SQUARE DL
• U+3398 ㎘ SQUARE KL

History[edit]

The first name of the litre was «cadil»; standards are shown at the Musée des Arts et Métiers in Paris.^[13]

The litre was introduced in France in 1795 as one of the new «republican units of measurement» and defined as one cubic decimetre.^[14]
One litre of liquid water has a mass of almost exactly one kilogram, due to the gram being defined in 1795 as one cubic centimetre of water at the temperature of melting ice.^[4]
The original decimetre length was 44.344 lignes, which was revised in 1798 to 44.3296 lignes. This made the original litre 1.000974 of today’s cubic decimetre. It was against this litre that the kilogram was constructed.

In 1879, the CIPM adopted the definition of the litre, with the symbol l (lowercase letter L).

In 1901, at the 3rd CGPM conference, the litre was redefined as the space occupied by 1 kg of pure water at the temperature of its maximum density (3.98 °C) under a pressure of 1 atm. This made the litre equal to about 1.000028 dm³ (earlier reference works usually put it at 1.000027 dm³).

In 1964, at the 12th CGPM conference, the original definition was reverted to, and thus the litre was once again defined in exact relation to the metre, as another name for the cubic decimetre, that is, exactly 1 dm³.^[5]

In 1979, at the 16th CGPM conference, the alternative symbol L (uppercase letter L) was adopted. It also expressed a preference that in the future only one of these two symbols should be retained, but in 1990 said it was still too early to do so.^[11]

Everyday usage[edit]

In spoken English, the symbol «mL» (for millilitre) can be pronounced as «mil». This can potentially cause confusion with some other measurement words such as:

1. «mm» for millimetre, a unit of length equal to one-thousandth of a metre
2. «mil» for thousandth of an inch
3. «mil«, a Scandinavian unit of length equal to 10 kilometres
4. «mil», unit of angular measurement

The abbreviation «cc» (for cubic centimetre, equal to a millilitre or mL) is a unit of the cgs system, which preceded the MKS system, which later evolved into the SI system. The abbreviation «cc» is still commonly used in many fields, including medical dosage and sizing for combustion engine displacement.

The microlitre (μL) has been known in the past as the lambda (λ), but this usage is now discouraged.^[15] In the medical field the microlitre is sometimes abbreviated as mcL on test results.^[16]

In the SI system, apart from prefixes for powers of 1000, use of the «centi» (10⁻²), «deci» (10⁻¹), «deca» (10⁺¹) and «hecto» (10⁺²) prefixes with litres is common. For example, in many European countries, the hectolitre is the typical unit for production and export volumes of beverages (milk, beer, soft drinks, wine, etc.) and for measuring the size of the catch and quotas for fishing boats; decilitres are common in Croatia, Switzerland and Scandinavia and often found in cookbooks, and restaurant and café menus; centilitres indicate the capacity of drinking glasses and of small bottles. In colloquial Dutch in Belgium, a «vijfentwintiger» and a «drieëndertiger» (literally «twenty-fiver» and «thirty-threer») are the common beer glasses, the corresponding bottles mention 25 cL and 33 cL. Bottles may also be 75 cL or half size at 37.5 cL for «artisanal» brews or 70 cL for wines or spirits. Cans come in 25 cL, 33 cL and 50 cL.^{[citation needed]} Similarly, alcohol shots are often marked in cL in restaurant menus, typically 3 cL (1.06 imp fl oz; 1.01 US fl oz).

In countries where the metric system was adopted as the official measuring system after the SI standard was established, common usage eschews prefixes that are not powers of 1000. For example, in Canada, Australia, and New Zealand, consumer beverages are labelled almost exclusively using litres and millilitres. An exception is in pathology, where for instance blood lead level^[17] and blood sugar level^[18] may be measured in micrograms/milligrams per decilitre.

For larger volumes, kilolitres, megalitres, and gigalitres, have been used by the Northern Territory Government for measuring water consumption, reservoir capacities and river flows,^[19] although cubic metres are also used. Cubic metres are generally used for non-liquid commodities, such as sand and gravel, or storage space.

See also[edit]

• Acre-foot
• Claude Émile Jean-Baptiste Litre
• Integrated nanolitre system

Notes[edit]

References[edit]

Bibliography[edit]

• Bureau International des Poids et Mesures (2006). «The International System of Units (SI)» (PDF). Retrieved 18 August 2008.
• Bureau International des Poids et Mesures. (2006). «The International System of Units (SI)» (on-line browser):
  • Table 6 (Non-SI units accepted for use with the International System). Retrieved 2008-08-24
• National Institute of Standards and Technology (11 November 2000). «Appendix C: General tables of units of measurement». NIST Handbook 44: Specifications, Tolerances, and Other Technical Requirements for Weighing and Measuring Devices. National Institute of Standards and Technology. Archived from the original on 10 December 2011. Retrieved 9 October 2006.
• National Institute of Standards and Technology. (December 2003). The NIST Reference on Constants, Units, and Uncertainty: International System of Units (SI) (web site):
  • Note on SI units. Retrieved 2008-08-24.
  • Recommending uppercase letter L. Retrieved 2008-08-24.
• Taylor, B.N. and Thompson, A. (Eds.). (2008a). The International System of Units (SI) Archived 3 June 2016 at the Wayback Machine. United States version of the English text of the eighth edition (2006) of the International Bureau of Weights and Measures publication Le Système International d’ Unités (SI) (Special Publication 330). Gaithersburg, MD: National Institute of Standards and Technology. Retrieved 2008-08-18.
• Taylor, B.N. and Thompson, A. (2008b). Guide for the Use of the International System of Units (Special Publication 811). Gaithersburg, MD: National Institute of Standards and Technology. Retrieved 2008-08-23.
• Turner, J. (Deputy Director of the National Institute of Standards and Technology). (16 May 2008).»Interpretation of the International System of Units (the Metric System of Measurement) for the United States». Federal Register Vol. 73, No. 96, p. 28432-3.
• UK National Physical Laboratory. Non-SI Units

From Wikipedia, the free encyclopedia

This article is about a common unit of volume. For the plant commonly known as litre, see Lithraea caustica.

«ltr.» redirects here. For letter, see Letter.

litre
One litre is the volume of a cube with 10 cm sides.
General information
Unit system	Non-SI unit accepted for use with SI
Unit of	volume
Symbol	L or l (or ℓ)[1]
Named after	litron
Conversions
1 L in …	… is equal to …
SI base unit	10−3 m3
U.S. customary	≈ 0.264 gallon

The litre (international spelling) or liter (American English spelling) (SI symbols L and l,^[1] other symbol used: ℓ) is a metric unit of volume. It is equal to 1 cubic decimetre (dm³), 1000 cubic centimetres (cm³) or 0.001 cubic metre (m³). A cubic decimetre (or litre) occupies a volume of 10 cm × 10 cm × 10 cm (see figure) and is thus equal to one-thousandth of a cubic metre.

The original French metric system used the litre as a base unit. The word litre is derived from an older French unit, the litron, whose name came from Byzantine Greek—where it was a unit of weight, not volume^[2]—via Late Medieval Latin, and which equalled approximately 0.831 litres. The litre was also used in several subsequent versions of the metric system and is accepted for use with the SI,^[3] although not an SI unit—the SI unit of volume is the cubic metre (m³). The spelling used by the International Bureau of Weights and Measures is «litre»,^[3] a spelling which is shared by most English-speaking countries. The spelling «liter» is predominantly used in American English.^[a]

One litre of liquid water has a mass of almost exactly one kilogramme, because the kilogramme was originally defined in 1795 as the mass of one cubic decimetre of water at the temperature of melting ice (0 °C).^[4] Subsequent redefinitions of the metre and kilogramme mean that this relationship is no longer exact.^[5]

Definition[edit]

A litre is a cubic decimetre, which is the volume of a cube 10 centimetres × 10 centimetres × 10 centimetres (1 L ≡ 1 dm³ ≡ 1000 cm³). Hence 1 L ≡ 0.001 m³ ≡ 1000 cm³; and 1 m³ (i.e. a cubic metre, which is the SI unit for volume) is exactly 1000 L.

From 1901 to 1964, the litre was defined as the volume of one kilogram of pure water at maximum density (+4 °C) and standard pressure. The kilogram was in turn specified as the mass of the International Prototype of the Kilogram (a specific platinum/iridium cylinder) and was intended to be of the same mass as the 1 litre of water referred to above. It was subsequently discovered that the cylinder was around 28 parts per million too large and thus, during this time, a litre was about 1.000028 dm³. Additionally, the mass–volume relationship of water (as with any fluid) depends on temperature, pressure, purity and isotopic uniformity. In 1964, the definition relating the litre to mass was superseded by the current one. Although the litre is not an SI unit, it is accepted by the CGPM (the standards body that defines the SI) for use with the SI. CGPM defines the litre and its acceptable symbols.

A litre is equal in volume to the millistere, an obsolete non-SI metric unit formerly customarily used for dry measure.

Explanation[edit]

Litres are most commonly used for items (such as fluids and solids that can be poured) which are measured by the capacity or size of their container, whereas cubic metres (and derived units) are most commonly used for items measured either by their dimensions or their displacements. The litre is often also used in some calculated measurements, such as density (kg/L), allowing an easy comparison with the density of water.

One litre of water has a mass of almost exactly one kilogram when measured at its maximal density, which occurs at about 4 °C. It follows, therefore, that 1000th of a litre, known as one millilitre (1 mL), of water has a mass of about 1 g; 1000 litres of water has a mass of about 1000 kg (1 tonne or megagram). This relationship holds because the gram was originally defined as the mass of 1 mL of water; however, this definition was abandoned in 1799 because the density of water changes with temperature and, very slightly, with pressure.

It is now known that the density of water also depends on the isotopic ratios of the oxygen and hydrogen atoms in a particular sample. Modern measurements of Vienna Standard Mean Ocean Water, which is pure distilled water with an isotopic composition representative of the average of the world’s oceans, show that it has a density of 0.999975±0.000001 kg/L at its point of maximum density (3.984 °C) under one standard atmosphere (101.325 kPa) of pressure.^[6]

SI prefixes applied to the litre[edit]

The litre, though not an official SI unit, may be used with SI prefixes. The most commonly used derived unit is the millilitre, defined as one-thousandth of a litre, and also often referred to by the SI derived unit name «cubic centimetre». It is a commonly used measure, especially in medicine, cooking and automotive engineering. Other units may be found in the table below, where the more often used terms are in bold. However, some authorities advise against some of them; for example, in the United States, NIST advocates using the millilitre or litre instead of the centilitre.^[7] There are two international standard symbols for the litre: L and l. In the United States the former is preferred because of the risk that (in some fonts) the letter l and the digit 1 may be confused.^[8]

Multiple	Name	Symbols	Equivalent volume
10−30 L	quectolitre	ql	qL	103 pm3	thousand cubic picometres
10−27 L	rontolitre	rl	rL	106 pm3	million cubic picometres
10−24 L	yoctolitre	yl	yL	nm3	cubic nanometre
10−21 L	zeptolitre	zl	zL	103 nm3	thousand cubic nanometres
10−18 L	attolitre	al	aL	106 nm3	million cubic nanometres
10−15 L	femtolitre	fl	fL	μm3	cubic micrometre
10−12 L	picolitre	pl	pL	103 μm3	thousand cubic micrometres
10−9 L	nanolitre	nl	nL	106 μm3	million cubic micrometres
10−6 L	microlitre	μl	μL	mm3	cubic millimetre
10−3 L	millilitre	ml	mL	cm3	cubic centimetre
10−2 L	centilitre	cl	cL	101 cm3	ten cubic centimetres
10−1 L	decilitre	dl	dL	102 cm3	hundred cubic centimetres
100 L	litre	l	L	dm3	cubic decimetre
101 L	decalitre	dal	daL	101 dm3	ten cubic decimetres
102 L	hectolitre	hl	hL	102 dm3	hundred cubic decimetres
103 L	kilolitre	kl	kL	m3	cubic metre
106 L	megalitre	Ml	ML	dam3	cubic decametre, 1 million litres
109 L	gigalitre	Gl	GL	hm3	cubic hectometre
1012 L	teralitre	Tl	TL	km3	cubic kilometre
1015 L	petalitre	Pl	PL	103 km3	thousand cubic kilometres
1018 L	exalitre	El	EL	106 km3	million cubic kilometres
1021 L	zettalitre	Zl	ZL	Mm3	cubic megametre
1024 L	yottalitre	Yl	YL	103 Mm3	thousand cubic megametres
1027 L	ronnalitre	Rl	RL	106 Mm3	million cubic megametres
1030 L	quettalitre	Ql	QL	Gm3	cubic gigametre

Non-metric conversions[edit]

Approx. value of 1 litre in non-metric units		Non-metric unit	Equivalent in litres
≈ 0.87987699	Imperial quart	1 Imperial quart	≡ 1.1365225 L
≈ 1.056688	U.S. quarts	1 U.S. quart	≡ 0.946352946 L
≈ 1.75975399	Imperial pints	1 Imperial pint	≡ 0.56826125 L
≈ 2.11337641	U.S. pints	1 U.S. pint	≡ 0.473176473 L
≈ 0.21996925	Imperial gallon	1 Imperial gallon	≡ 4.54609 L
≈ 0.2641720523	U.S. gallon	1 U.S. gallon	≡ 3.785411784 L
≈ 0.0353146667	cubic foot	1 cubic foot	≡ 28.316846592 L
≈ 61.023744	cubic inches	1 cubic inch	≡ 0.016387064 L
≈ 35.19508	Imperial fluid ounces	1 Imperial fluid ounce	≡ 28.4130625 mL
≈ 33.814023	U.S. fluid ounces	1 U.S. fluid ounce	≡ 29.5735295625 mL

See also Imperial units and US customary units.

Rough conversions[edit]

One litre is slightly larger than a US liquid quart and slightly less than an imperial quart or one US dry quart. A mnemonic for its volume relative to an imperial pint is «a litre of water’s a pint and three-quarters»; this is very close, as a litre is actually 1.75975399 pints.

A cubic foot has an exact volume of 28.316846592 litres.

Symbol[edit]

Originally, the only symbol for the litre was l (lowercase letter L), following the SI convention that only those unit symbols that abbreviate the name of a person start with a capital letter. In many English-speaking countries, however, the most common shape of a handwritten Arabic digit 1 is just a vertical stroke; that is, it lacks the upstroke added in many other cultures. Therefore, the digit «1» may easily be confused with the letter «l». In some computer typefaces, the two characters are barely distinguishable. As a result, L (uppercase letter L) was adopted by the CIPM as an alternative symbol for litre in 1979.^[9] The United States National Institute of Standards and Technology now recommends the use of the uppercase letter L,^[10] a practice that is also widely followed in Canada and Australia. In these countries, the symbol L is also used with prefixes, as in mL and μL, instead of the traditional ml and μl used in Europe. In the UK and Ireland, as well as the rest of Europe, lowercase l is used with prefixes, though whole litres are often written in full (so, «750 ml» on a wine bottle, but often «1 litre» on a juice carton). In 1990, the International Committee for Weights and Measures stated that it was too early to choose a single symbol for the litre.^[11]

Script l [edit]

Prior to 1979, the symbol ℓ came into common use in some countries;^{[citation needed]} for example, it was recommended by South African Bureau of Standards publication M33 and Canada in the 1970s. This symbol can still be encountered occasionally in some English-speaking and European countries like Germany, and its use is ubiquitous in Japan and South Korea.

Fonts covering the CJK characters usually include not only the script small ℓ but also four precomposed characters: ㎕, ㎖, ㎗, and ㎘ for the microlitre, millilitre, decilitre and kilolitre to allow correct rendering for vertically written scripts. These have Unicode equivalents for compatibility, which are not recommended for use with new documents:^[12]

• U+2113 ℓ SCRIPT SMALL L
• U+3395 ㎕ SQUARE MU L
• U+3396 ㎖ SQUARE ML
• U+3397 ㎗ SQUARE DL
• U+3398 ㎘ SQUARE KL

History[edit]

The first name of the litre was «cadil»; standards are shown at the Musée des Arts et Métiers in Paris.^[13]

The litre was introduced in France in 1795 as one of the new «republican units of measurement» and defined as one cubic decimetre.^[14]
One litre of liquid water has a mass of almost exactly one kilogram, due to the gram being defined in 1795 as one cubic centimetre of water at the temperature of melting ice.^[4]
The original decimetre length was 44.344 lignes, which was revised in 1798 to 44.3296 lignes. This made the original litre 1.000974 of today’s cubic decimetre. It was against this litre that the kilogram was constructed.

In 1879, the CIPM adopted the definition of the litre, with the symbol l (lowercase letter L).

In 1901, at the 3rd CGPM conference, the litre was redefined as the space occupied by 1 kg of pure water at the temperature of its maximum density (3.98 °C) under a pressure of 1 atm. This made the litre equal to about 1.000028 dm³ (earlier reference works usually put it at 1.000027 dm³).

In 1964, at the 12th CGPM conference, the original definition was reverted to, and thus the litre was once again defined in exact relation to the metre, as another name for the cubic decimetre, that is, exactly 1 dm³.^[5]

In 1979, at the 16th CGPM conference, the alternative symbol L (uppercase letter L) was adopted. It also expressed a preference that in the future only one of these two symbols should be retained, but in 1990 said it was still too early to do so.^[11]

Everyday usage[edit]

In spoken English, the symbol «mL» (for millilitre) can be pronounced as «mil». This can potentially cause confusion with some other measurement words such as:

1. «mm» for millimetre, a unit of length equal to one-thousandth of a metre
2. «mil» for thousandth of an inch
3. «mil«, a Scandinavian unit of length equal to 10 kilometres
4. «mil», unit of angular measurement

The abbreviation «cc» (for cubic centimetre, equal to a millilitre or mL) is a unit of the cgs system, which preceded the MKS system, which later evolved into the SI system. The abbreviation «cc» is still commonly used in many fields, including medical dosage and sizing for combustion engine displacement.

The microlitre (μL) has been known in the past as the lambda (λ), but this usage is now discouraged.^[15] In the medical field the microlitre is sometimes abbreviated as mcL on test results.^[16]

In the SI system, apart from prefixes for powers of 1000, use of the «centi» (10⁻²), «deci» (10⁻¹), «deca» (10⁺¹) and «hecto» (10⁺²) prefixes with litres is common. For example, in many European countries, the hectolitre is the typical unit for production and export volumes of beverages (milk, beer, soft drinks, wine, etc.) and for measuring the size of the catch and quotas for fishing boats; decilitres are common in Croatia, Switzerland and Scandinavia and often found in cookbooks, and restaurant and café menus; centilitres indicate the capacity of drinking glasses and of small bottles. In colloquial Dutch in Belgium, a «vijfentwintiger» and a «drieëndertiger» (literally «twenty-fiver» and «thirty-threer») are the common beer glasses, the corresponding bottles mention 25 cL and 33 cL. Bottles may also be 75 cL or half size at 37.5 cL for «artisanal» brews or 70 cL for wines or spirits. Cans come in 25 cL, 33 cL and 50 cL.^{[citation needed]} Similarly, alcohol shots are often marked in cL in restaurant menus, typically 3 cL (1.06 imp fl oz; 1.01 US fl oz).

In countries where the metric system was adopted as the official measuring system after the SI standard was established, common usage eschews prefixes that are not powers of 1000. For example, in Canada, Australia, and New Zealand, consumer beverages are labelled almost exclusively using litres and millilitres. An exception is in pathology, where for instance blood lead level^[17] and blood sugar level^[18] may be measured in micrograms/milligrams per decilitre.

For larger volumes, kilolitres, megalitres, and gigalitres, have been used by the Northern Territory Government for measuring water consumption, reservoir capacities and river flows,^[19] although cubic metres are also used. Cubic metres are generally used for non-liquid commodities, such as sand and gravel, or storage space.

See also[edit]

• Acre-foot
• Claude Émile Jean-Baptiste Litre
• Integrated nanolitre system

Notes[edit]

References[edit]

Bibliography[edit]

• Bureau International des Poids et Mesures (2006). «The International System of Units (SI)» (PDF). Retrieved 18 August 2008.
• Bureau International des Poids et Mesures. (2006). «The International System of Units (SI)» (on-line browser):
  • Table 6 (Non-SI units accepted for use with the International System). Retrieved 2008-08-24
• National Institute of Standards and Technology (11 November 2000). «Appendix C: General tables of units of measurement». NIST Handbook 44: Specifications, Tolerances, and Other Technical Requirements for Weighing and Measuring Devices. National Institute of Standards and Technology. Archived from the original on 10 December 2011. Retrieved 9 October 2006.
• National Institute of Standards and Technology. (December 2003). The NIST Reference on Constants, Units, and Uncertainty: International System of Units (SI) (web site):
  • Note on SI units. Retrieved 2008-08-24.
  • Recommending uppercase letter L. Retrieved 2008-08-24.
• Taylor, B.N. and Thompson, A. (Eds.). (2008a). The International System of Units (SI) Archived 3 June 2016 at the Wayback Machine. United States version of the English text of the eighth edition (2006) of the International Bureau of Weights and Measures publication Le Système International d’ Unités (SI) (Special Publication 330). Gaithersburg, MD: National Institute of Standards and Technology. Retrieved 2008-08-18.
• Taylor, B.N. and Thompson, A. (2008b). Guide for the Use of the International System of Units (Special Publication 811). Gaithersburg, MD: National Institute of Standards and Technology. Retrieved 2008-08-23.
• Turner, J. (Deputy Director of the National Institute of Standards and Technology). (16 May 2008).»Interpretation of the International System of Units (the Metric System of Measurement) for the United States». Federal Register Vol. 73, No. 96, p. 28432-3.
• UK National Physical Laboratory. Non-SI Units

При написании значений величин применяют обозначения единиц буквами или специальными знаками (…«, …, …„), причем устанавливают два вида буквенных обозначений: международное (с использованием букв латинского или греческого алфавита) и русское (с использованием букв русского алфавита). Устанавливаемые стандартом обозначения единиц приведены в таблицах 1—8.

8.2 Буквенные обозначения единиц печатают прямым шрифтом. В обозначениях единиц точку как знак сокращения не ставят.

8.3 Обозначения единиц помещают за числовыми значениями величин и в строку с ними (без переноса на следующую строку). Числовое значение, представляющее собой дробь с косой чертой, стоящее перед обозначением единицы, заключают в скобки.

Между последней цифрой числа и обозначением единицы оставляют пробел.
Правильно: Неправильно:
100 kW; 100 кВт
80 %
20 °C
(1/60) s–1. 100kW; 100кВт
80%
20°C
1/60s–1.

Исключения составляют обозначения в виде знака, поднятого над строкой, перед которыми пробел не оставляют.
Правильно: Неправильно:
20°. 20 °.

36 классификаторов на одном сайте —
коды, расшифровка, описание

Быстрый поиск записи классификатора по коду:

Всего найдено: 29

Здравствуйте!
Подскажите пожалуйста, как правильно пишется аббревиатура единицы измерения реактивной электрической мощности киловольт-ампер реактивный: кВАр, кВар или квар?

Ответ справочной службы русского языка

Корректно: кВАр.

Добрый день! Пожалуйста не оставьте в беде! Целая баталия разразилась по этому вопросу и Вы — моя последняя надежда! Нужен ли пробел между числительным и сокращением или значком, обозначающим единицы измерения, например «90 мм» или же «20%»? Это все дело вкуса или существует на этот счет правило?
Я буду очень рада любому ответу! Спасибо Вам большое!

Ответ справочной службы русского языка

Знаки №, % и § отделяют пробелом от числа (в типографской терминологии – «отбивают от цифр на полукегельную» – см. «Справочник издателя и автора» А. Э. Мильчина, Л. К. Чельцовой). Между числом и буквенным сокращением единицы измерения (км, мм, см, кг, г и т. п.) пробел обязателен: 90 мм

Добрый день. Подскажите, пож-ста, склоняется ли слово иностранного происхождения «бар» (единица измерения давления) по падежам и числам? 1 бар, а когда, например, 8? бар или баров?

Ответ справочной службы русского языка

Слово бар (название единицы измерения) склоняется. Следует иметь в виду, что у этого слова есть счетная форма родительного падежа, совпадающая с формой именительного падежа. Правильно: 1 бар, 8 бар.

Добрый день! Скажите, пожалуйста, склоняется ли фамилия Тесла? Я имею в виду физика Николу Тесла? Спасибо!

Ответ справочной службы русского языка

Имя и фамилия физика обычно склоняются (правильно: изобретение Николы Теслы). Несклоняемой остается эта фамилия в составе технического наименования (трансформатор Тесла) и, по рекомендации некоторых словарей, в качестве названия единицы измерения магнитной индукции (тесла).

Правильно ли написание
«24-вольтовая лампа»,
ведь Вольт — имя собственное?

Ответ справочной службы русского языка

Название единицы измерения — вольт — пишется строчными буквами. Строчными буквами пишется также прилагательное, содержащее в себе компонент *вольтовый или *вольтный. 

Скажите, пожалуйста, как правильно писать единицы измерения, например: м3/сут. или м3/чел.·сут.
Нужно ли ставить точки в сокращениях чел. и сут.?

Ответ справочной службы русского языка

Сокращение чел. (человек) пишется с точкой.

Написание сокращения сут. (сутки) с точкой зафиксировано в «Русском орфографическом словаре» РАН, хотя согласно ГОСТу (см. «Сокращение слов и словосочетаний по ГОСТ Р 7.0.12-2011») это сокращение должно быть написано без точки. Видимо, можно дать такую рекомендацию: при составлении документов, технических текстов следовать ГОСТу, а в обычной письменной речи оформлять эти сокращения так, как рекомендовано орфографическим словарем.

Есть ли способ записи прилагательных типа «семимиллиметровый» с сокращением единицы измерения (напр., 7-мм-й)? В предыдущих Ваших ответах предлагался только вариант «7-миллиметровый».

Ответ справочной службы русского языка

В специальных изданиях возможен вариант сокращения: 7-мм.

Встречаю в статьях такие примеры «…на 25 и более мм рт. ст.» или «15 и менее литров».
Правомерно ли отрывать единицы измерения в этих случаях? Или можно, если писать единицы без сокращения (как в случае с литрами)?

Ответ справочной службы русского языка

Верно: на 25 мм рт. ст., на 15 литров (15 л) и менее.

Подскажите, пожалуйста, как правильно: «снизится с 12 до 10%» или «снизится с 12% до 10%»? Распространяется ли это правило на все единицы измерения?
С уважением, Никита Золотарев.

Ответ справочной службы русского языка

Корректно: _снизится с 12 до 10 %_.

Уважаемая Справка! Мой комментарий к вопросу 209637. Согласно ГОСТу 8.417-2002 (см. раздел 5, таблица 1) единица измерения времени – секунда, она является одной из основных единиц международной системы единиц СИ, кроме нее к основным относятся метр (м), килограмм (кг), ампер (а), кельвин (К), моль (моль) и кандела (кд). От них образованы производные единицы измерения. Точки после обозначения системных единиц не ставятся. Есть еще внесистемные единицы, здесь точки иногда ставятся, например, а. е. м. – атомная единица массы.

Ответ справочной службы русского языка

Большое спасибо за дополнение!

Ответ на мой вопрос от 03.11.2006 или не получил, или не заметил. Поэтому повторяю:

В ответе Справки на № 208758 сказано: сокращенные единицы измерения пишутся без точек. Ранее, в ответе на 200931: правильно: мин. и м. — минута, сек. и с. — секунда, ч. — час.
Чем объяснить противоречия в ответах Справки? Может быть требуется уточнение: сокращённые единицы длины и массы (м, км, кг) пишутся без точки, а единиц времени (м., ч., с.) — с точкой? Кстати, сокращения минуты (м.) и метра (м) именно точкой и отличаются.

Ответ справочной службы русского языка

Противоречия нет. Сокращенные единицы измерения — это, например, кг (килограмм), ц (центнер), тс (тонна-сила), сб (стильб), м (метр). Минута и секунда не относятся к единицам измерения, это единицы времени.

Здравствуйте! Проясните мне пожалуйста такую ситуацию, в каких случаях при сокращениях ставят точку (ч.). Вчастности, меня интересует (км, м). Из других источников узнала, что при обозначении стандартных физических велечин (м, мм, кг) точка не ставится. Хотелось бы узнать существует ли какое-либо правило русского языка или точку упразднил «народ». И будет ли считаться ошибкой её отсутствие в деловом письме? Заранее спасибо!

Ответ справочной службы русского языка

Сокращенные единицы измерения пишутся без точек. Грамотное написание сокращений в деловом письме считаем уместным.

Добрый день. Ответьте, будьте любезны, как правильно обозначаются единицы измерения реактивной мощности — вар или ВАр?? В Интернете нашла и одно, и другое написание, но как правильно?
С уважением, Надежда Николаевна.

Ответ справочной службы русского языка

В орфографическом словаре такого сокращения пока нет. Сайт www.sokr.ru предлагает вариант со строчными: _вар_.

Добрый день!
Очень нуждаюсь в прояснении вопроса о правописании сокращений, обозначающих единицы измерения: секунды, минуты, миллиарды, миллионы — везде разночтения.
Хотелось бы также справиться, как пишется обозначение единицы напряжения сжатия: кПа, КПа, кПА?
Спасибо.

Ответ справочной службы русского языка

Согласно второму изданиию «Русского орфографического словаря», вышедшему в 2005 году, корректны следующие сокращения: _сек._ и _с._ (секунда), _мин._ и _м._ (минута), _млрд_ без точки (миллиард), _млн_ без точки (миллион), _кПа_ (килопаскаль).

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По запросу литр нашлось 43 сокращения:

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