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A one-US-gallon gas can showing "U.S. Gallon" marking (for US use), imperial gallons (for Canadian use), and litres
General information
Unit ofVolume
Conversions (imperial)
1 imp gal in ...... is equal to ...
    SI units   4.54609 L
   US customary units   1.200950 US gal
   US customary units   277.4194 in3
Conversions (US)
1 US gal in ...... is equal to ...
   SI units   3.785411784 L
   Imperial units   0.8326742 imp gal
   Imperial units   231 in3
   US dry gallon   0.859367 US dry gal

The gallon is a unit of volume in imperial units and United States customary units. Three different versions are in current use:


There are four quarts in a gallon and eight pints in a gallon, which have different volumes in different systems.

The IEEE standard symbol for both US (liquid) and imperial gallon is gal, [1] not to be confused with the gal (symbol: Gal), a CGS unit of acceleration.


The gallon currently has one definition in the imperial system, and two definitions (liquid and dry) in the US customary system. Historically, there were many definitions and redefinitions.

English system gallons

There were a number of systems of liquid measurements in the United Kingdom prior to the 19th century. [2]

Imperial gallon

A Shell petrol station selling 2* and 4* (leaded petrol) by the gallon in the UK, circa 1980. Shell petrol station in the UK.jpg
A Shell petrol station selling 2* and 4* (leaded petrol) by the gallon in the UK, circa 1980.

The British imperial gallon is defined as exactly 4.54609 dm3. [3] It is used in some Commonwealth countries, and until 1976 was based on the volume of 10 pounds (4.5359237 kg) of water at 62 degrees Fahrenheit (16.(6) °C). [4] [5] There are four quarts in a gallon, the imperial pint is defined as 0.56826125 litres (18 gallon) and there are 20 imperial fluid ounces in an imperial pint. [3]

US liquid gallon

A fuel station in the United States displaying fuel prices per US gallon US petrol pump.jpg
A fuel station in the United States displaying fuel prices per US gallon

The US liquid gallon (frequently called simply "gallon") is legally defined as 231 cubic inches, which is exactly 3.785411784 litres. [6] [7] A US liquid gallon of water weighs about 8.34 pounds or 3.78 kilograms at 62 °F (17 °C), making it about 16.6% lighter than the imperial gallon. There are four quarts in a gallon, two pints in a quart and 16 US fluid ounces in a US pint, which makes the US fluid ounce equal to 1/128 of a US gallon. In order to overcome the effects of expansion and contraction with temperature when using a gallon to specify a quantity of material for purposes of trade, it is common to define the temperature at which the material will occupy the specified volume. For example, the volume of petroleum products [8] and alcoholic beverages [9] are both referenced to 60 °F (15.6 °C) in government regulations.

US dry gallon

Since the dry measure is one-eighth of a US Winchester bushel of 2150.42 cubic inches, it is equal to exactly 268.8025 cubic inches, which is 4.40488377086 L. [10] The US dry gallon is not used in commerce, and is also not listed in the relevant statute, which jumps from the dry pint to the bushel. [11]

Worldwide usage

Petrol units used in the world:
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US gallon
Imperial gallon
No data Gasoline unit.svg
Petrol units used in the world:
  US gallon
  Imperial gallon
  No data

Imperial gallon

As of 2021, the imperial gallon continues to be used as the standard petrol unit in four British Overseas Territories, which are Anguilla, [12] the British Virgin Islands, [13] the Cayman Islands, [14] and Montserrat. [15] [16] The imperial gallon is also the standard petrol unit in six countries, which are Antigua and Barbuda, [17] Dominica, [18] Grenada, [19] [20] Saint Christopher and Nevis, [21] Saint Lucia, [22] and Saint Vincent and the Grenadines. [23]

All of the countries and territories which use the imperial gallon as their petrol unit also use miles per hour for speed limits and drive on the left side of the road.

The United Arab Emirates stopped selling petrol by the imperial gallon in 2010 and switched to the litre, with Guyana following suit in 2013. [24] [25] [26]

Burma switched from the imperial gallon to the litre in 2014. [27]

Antigua and Barbuda moved to using litres in 2015. [28] [17]

The gallon was removed from the list of legally defined primary units of measure catalogued in the EU directive 80/181/EEC for trading and official purposes, with effect from 31 December 1994. Under the directive the gallon could still be used, but only as a supplementary or secondary unit. [29] One of the effects of this directive was that the United Kingdom amended its own legislation to replace the gallon with the litre as a primary unit of measure in trade and in the conduct of public business, effective from 30 September 1995. [30] [31] [32] However within the United Kingdom and Ireland, barrels and large containers of beer, oil and other fluids are sometimes marked in imperial gallons.

Ireland also passed legislation in response to the EU directive, with the effective date being 31 December 1993. [33] Though the gallon has ceased to be a primary unit of trade, it can still be legally used in both the UK and Ireland as a supplementary unit.

Miles per imperial gallon is used as the primary fuel economy unit in the United Kingdom and as a supplementary unit in Canada on official documentation. [34] [35] [36]

In the Middle East, water-chiller bottles come in multiples of the imperial gallon.

US liquid gallon

Other than the United States itself, petrol is issued by the US gallon in Belize, Colombia, Dominican Republic, Ecuador, Guatemala, Haiti, Honduras, Liberia, Nicaragua, and Peru.

Petrol is also sold by the US gallon in the Marshall Islands, Federated States of Micronesia, and Palau, all three of which are associated with the United States.

Despite its status as a US territory, and unlike American Samoa, [37] the Northern Mariana Islands, [38] Guam, [39] and the US Virgin Islands, [40] Puerto Rico ceased selling petrol by the US gallon in 1980. [41]

Panama stopped selling petrol in US gallons in 2013 and uses litres.

El Salvador stopped selling petrol in US gallons in June 2021 and now uses litres. [42]

In the Turks and Caicos Islands, both the US gallon and imperial gallon are used. This is due to an increase in tax duties which was disguised by levying the same duty on the US gallon (3.79 L) as was previously levied on the Imperial gallon (4.55 L). [43]

The Bahamas also uses both the US gallon and imperial gallon. [44] [45]

Relationship to other units

Both the US liquid and imperial gallon are divided into four quarts (quarter gallons), which in turn are divided into two pints, which in turn are divided into two cups, which in turn are further divided into two gills. Thus, both gallons are equal to four quarts, eight pints, sixteen cups, or thirty-two gills.

The imperial gill is further divided into five fluid ounces, whereas the US gill is divided into four fluid ounces, meaning an imperial fluid ounce is 1/20 of an imperial pint, or 1/160 of an imperial gallon, while a US fluid ounce is 1/16 of a US pint, or 1/128 of a US gallon. Thus, the imperial gallon, quart, pint, cup and gill are approximately 20% larger than their US counterparts, meaning these are not interchangeable, but the imperial fluid ounce is only approximately 4% smaller than the US fluid ounce, meaning these are often used interchangeably.

Historically, a common bottle size for liquor in the US was the "fifth", i.e. one-fifth of a US gallon (or one-sixth of an imperial gallon). While spirit sales in the US were switched to metric measures in 1976, a 750 mL bottle is still sometimes known as a "fifth". [46] [47]


An American milk bottle with a volume of one US gallon Bottle of milk.jpg
An American milk bottle with a volume of one US gallon

The term derives most immediately from galun, galon in Old Northern French, but the usage was common in several languages, for example jale in Old French and gęllet (bowl) in Old English. This suggests a common origin in Romance Latin, but the ultimate source of the word is unknown. [48]

The gallon originated as the base of systems for measuring wine and beer in England. The sizes of gallon used in these two systems were different from each other: the first was based on the wine gallon (equal in size to the US gallon), and the second one either the ale gallon or the larger imperial gallon.

By the end of the 18th century, there were three definitions of the gallon in common use:

The corn or dry gallon is used (along with the dry quart and pint) in the United States for grain and other dry commodities. It is one-eighth of the (Winchester) bushel, originally defined as a cylindrical measure of 18+1/2 inches in diameter and 8 inches in depth, which made the dry gallon 8 in × (9+1/4 in)2 × π ≈ 2150.42017 cubic inches. The bushel was later defined to be 2150.42 cubic inches exactly, thus making its gallon exactly 268.8025 in3 (4.40488377086 L); in previous centuries, there had been a corn gallon of between 271 and 272 cubic inches.

The wine, fluid, or liquid gallon has been the standard US gallon since the early 19th century. The wine gallon, which some sources relate to the volume occupied by eight medieval merchant pounds of wine, was at one time defined as the volume of a cylinder 6 inches deep and 7 inches in diameter, i.e. 6 in × (3+1/2 in)2 × π ≈ 230.907 06 cubic inches. It was redefined during the reign of Queen Anne in 1706 as 231 cubic inches exactly, the earlier definition with π approximated to 22/7. Although the wine gallon had been used for centuries for import duty purposes, there was no legal standard of it in the Exchequer, while a smaller gallon (224 cu in) was actually in use, requiring this statute; it remains the US definition today.

In 1824, Britain adopted a close approximation to the ale gallon known as the imperial gallon, and abolished all other gallons in favour of it. Inspired by the kilogram-litre relationship, the imperial gallon was based on the volume of 10 pounds of distilled water weighed in air with brass weights with the barometer standing at 30 inches of mercury and at a temperature of 62 °F.

In 1963, this definition was refined as the space occupied by 10 pounds of distilled water of density 0.998859 g/mL weighed in air of density 0.001217 g/mL against weights of density 8.136 g/mL (the original "brass" was refined as the densities of brass alloys vary depending on metallurgical composition), which was calculated as 4.546091879 L to ten significant figures. [4]

The precise definition of exactly 4.54609 cubic decimetres (also 4.54609 L, ≈ 277.419433 in3) came after the litre was redefined in 1964. This was adopted shortly afterwards in Canada, and adopted in 1976 in the United Kingdom. [4]

Sizes of gallons

Historically, gallons of various sizes were used in many parts of Western Europe. In these localities, it has been replaced as the unit of capacity by the litre.

Comparison of gallons
(gal/cu ft)
Weight as
water at 62 °F
Cylindrical approximation
(cu in)(dm3)Diameter
Volume rel.
Current gallons
2313.785411784Statute of 5 Queen Anne (UK wine gallon, standard US gallon)7.488.33760.04
268.80254.40488377086Winchester, statute of 13 & 14 William III (corn gallon, US dry gallon)6.439.7118.510.00001
≈ 277.41944.54609Standard imperial gallon≈ 6.23105⅔110.0002
Historic gallons
216 (Roman unciae)≈ 3.53961Roman congius 87.85110.01
224≈ 3.67070Preserved at the Guildhall, London (old UK wine gallon)7.718.0993.50.6
264.8≈ 4.33929Ancient Rumford quart (1228)6.539.577.560.1
265.5≈ 4.35077Exchequer (Henry VII, 1497, with rim)6.519.591320.01
266.25≈ 4.36306Ancient Rumford (1228)     
271≈ 4.44089Exchequer (1601, E.) (old corn gallon)6.389.794.5170.23
272≈ 4.45728Corn gallon (1688)     
≈ 277.2026≈ 4.54254Statute of 12 Anne (coal gallon) = 33/32 corn gallons6.2310   
≈ 277.274≈ 4.54370Imperial gallon, as originally determined in 18246.2310   
≈ 277.41954.546091879Imperial gallon as re-determined in 1895 and defined in 1963≈ 6.2310   
278≈ 4.55560Exchequer (Henry VII, with copper rim)6.2110.04   
278.4≈ 4.56216Exchequer (1601 and 1602 pints)6.2110.06   
280≈ 4.58838Exchequer (1601 quart)6.1710.1   
282≈ 4.62115Treasury (beer and ale gallon pre-1824)6.1310.2   

Related Research Articles

Imperial units System of units that were implemented on 1 January 1826 in the British Empire

The imperial system of units, imperial system or imperial units is the system of units first defined in the British Weights and Measures Act 1824 and continued to be developed through a series of Weights and Measures Acts and amendments.

Litre Unit of volume

The litre or liter 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 occupies a volume of 10 cm × 10 cm × 10 cm and is thus equal to one-thousandth of a cubic metre.

United States customary units System of units of measurement commonly used in the United States

United States customary units form a system of measurement units commonly used in the United States and U.S. territories since being formalized in 1832. The United States customary system developed from English units which were in use in the British Empire before the U.S. became an independent country. The United Kingdom's system of measures was overhauled in 1824 to create the imperial system, which was officially adopted in 1826, changing the definitions of some of its units. Subsequently, while many U.S. units are essentially similar to their imperial counterparts, there are significant differences between the systems.

Cooking weights and measures

In recipes, quantities of ingredients may be specified by mass, by volume, or by count.

Pint Unit of volume in the imperial and US systems

The pint is a unit of volume or capacity in both the imperial and United States customary measurement systems. In both of those systems it is traditionally one eighth of a gallon. The British imperial pint is about 20% larger than the American pint because the two systems are defined differently. Almost all other countries have standardized on the metric system, so the size of what may be called a pint, from the French la pinte, varies depending on local custom.

The quart is an English unit of volume equal to a quarter gallon. Three kinds of quarts are currently used: the liquid quart and dry quart of the US customary system and the imperial quart of the British imperial system. All are roughly equal to one liter. It is divided into two pints or four cups. Historically, the exact size of the quart has varied with the different values of gallons over time and in reference to different commodities.

Fluid ounce unit of volume

A fluid ounce is a unit of volume typically used for measuring liquids. Various definitions have been used throughout history, but only two are still in common use: the British Imperial and the United States customary fluid ounce.

Barrel (unit) Series of units for volume measurement

A barrel is one of several units of volume applied in various contexts; there are dry barrels, fluid barrels, oil barrels, and so forth. For historical reasons the volumes of some barrel units are roughly double the volumes of others; volumes in common use range approximately from 100 to 200 litres. In many connections the term drum is used almost interchangeably with barrel.

A system of measurement is a collection of units of measurement and rules relating them to each other. Systems of measurement have historically been important, regulated and defined for the purposes of science and commerce. Systems of measurement in use include the International System of Units (SI), the modern form of the metric system, the British imperial system, and the United States customary system.

English units are the units of measurement used in England up to 1826, which evolved as a combination of the Anglo-Saxon and Roman systems of units. Various standards have applied to English units at different times, in different places, and for different applications.

Measuring cup

A measuring cup is a kitchen utensil used primarily to measure the volume of liquid or bulk solid cooking ingredients such as flour and sugar, especially for volumes from about 50 mL (2 fl oz) upwards. Measuring cups are also used to measure washing powder, liquid detergents and bleach for clothes washing. The cup will usually have a scale marked in cups and fractions of a cup, and often with fluid measure and weight of a selection of dry foodstuffs.

Cup (unit) Cooking measure of volume

The cup is a cooking measure of volume, commonly associated with cooking and serving sizes. It is traditionally equal to one-half US pint (236.6 ml). Because actual drinking cups may differ greatly from the size of this unit, standard measuring cups may be used, with a metric cup being 250 millilitres.

Comparison of the imperial and US customary measurement systems

Both the British Imperial and United States customary systems of measurement derive from earlier English systems used in the Middle Ages, that were the result of a combination of the local Anglo-Saxon units inherited from Germanic tribes and Roman units brought by William the Conqueror after the Norman Conquest of England in 1066.

Alcohol measurements are units of measurement for determining amounts of beverage alcohol.

Capacities of wine casks were formerly measured and standardised according to a specific system of English units. The various units were historically defined in terms of the wine gallon so varied according to the definition of the gallon until the adoption of the Queen Anne wine gallon in 1707. In the United Kingdom and its colonies the units were redefined with the introduction of the imperial system whilst the Queen Anne wine gallon was adopted as the standard US liquid gallon.

Capacities of brewery casks were formerly measured and standardised according to a specific system of English units. The system was originally based on the ale gallon of 282 cubic inches. In United Kingdom and its colonies, with the adoption of the imperial system in 1824, the units were redefined in terms of the slightly smaller imperial gallon. The older units continued in use in the United States.

Fifth (unit)

A fifth is a unit of volume formerly used for wine and distilled beverages in the United States, equal to one fifth of a US liquid gallon, or 25+35 U.S. fluid ounces ; it has been superseded by the metric bottle size of 750 ml, sometimes called a metric fifth, which is the standard capacity of wine bottles worldwide and is approximately 1% smaller.

The dry gallon, also known as the corn gallon or grain gallon, is a historic British dry measure of volume that was used to measure grain and other dry commodities and whose earliest recorded official definition, in 1303, was the volume of 8 pounds (3.6 kg) of wheat. It is not used in the US customary system – though it implicitly exists since the US dry measures of bushel, peck, quart, and pint are still used – and is not included in the National Institute of Standards and Technology handbook that many US states recognize as the authority on measurement law.

Imperial and US customary measurement systems

The imperial and US customary measurement systems are both derived from an earlier English system of measurement which in turn can be traced back to Ancient Roman units of measurement, and Carolingian and Saxon units of measure.

A number of units of measurement were used in South Africa to measure quantities like length, mass, capacity, etc. The Imperial system of measurements was made standard in 1922 and the metric system was adopted in 1970.


  1. IEEE Std 260.1-2014
  2. Ricketts, Carl. "Capacity Measures of the British Isles" (PDF). Retrieved 6 September 2016.
  3. 1 2 "Weights and Measures Act 1985, chapter 72, schedule 1". The National Archives on behalf of HM Government. Retrieved 7 June 2019.
  4. 1 2 3 BS 350:Part 1:1974 Conversion factors and tables Part 1. Basis of tables. Conversion factors (AMD 4153 ed.). British Standards Institution. 1983. p. Foreword. Before that date (November 1976) the definition in the Weights and Measures Act 1963 was such that the gallon could be calculated to be 4.546 091 879 dm3 to ten significant figures... The return, in November 1976, by precise definition to what had earlier been used as an approximation for the value of the gallon (i.e. 4.546 09 dm3)...
  5. BS 350:Part 1:1974 Conversion factors and tables Part 1. Basis of tables. Conversion factors (prior to Amendment No.1 1983 ed.). British Standards Institution. 1974. p. 10. the UK gallon (imp gal), defined in Schedule 1 of the Weights and Measures Act 1963, as the space occupied by 10 pounds of distilled water under certain conditions specified in the schedule.
  6. "NIST Handbook 44 - 2012 Edition Appendix C "General Tables of Units of Measurement"". 26 October 2012. p. C-5.
  7. Uniform Laws and Regulations in the areas of legal metrology and engine fuel quality (PDF). US Department of Commerce, National Institute of Standards and Technology. 2011. pp. 9–13, 69.
  8. "State of New Hampshire Dept of Weights and Measure" (PDF). Archived from the original (PDF) on 13 April 2012.
  9. "27 CFR section 5.21" (PDF).
  10. "US Dry Conversion Calculator". High accuracy calculation for life or science. Retrieved 24 October 2019.
  11. Authorized tables , US Code, Title 15, ch. 6, subchapter I, sec. 205, accessed 19 July 2008.
  12. "Anguilla Renewable Energy Integration Project Final Report" (PDF). Anguilla RE Integration Final Report. Government of Anguilla Ministry of Infrastructure, Communications, Utilities, and Housing (MICUH). 19 October 2012. p. 104. Retrieved 13 October 2013. In 2008—the most recent year where WTI crude oil averaged US$100 per barrel—ANGLEC paid an average of about US$4 per imperial gallon (imp gal) for diesel.
  13. Walker, William (5 September 2012). "Biwater project draws scrutiny". Archived from the original on 2 October 2013. Retrieved 30 September 2013.
  14. Wilson, Stuart (9 May 2013). "Fuel costs driven by factors". Cayman Compass.
  15. "Petrol price increases, diesel decreases, cost of living goes up". The Montserrat Reporter. 30 November 2012.
  16. Htin Lynn Aung (22 September 2017). "Fuel prices on the rise". The Myanmar Times .
  17. 1 2 "Government of Antigua and Barbuda". Retrieved 5 May 2021.
  18. "Photo of the day: Up and up it goes". Dominica News Online. 10 May 2011.
  19. Grenada: Third Review Under the Three-Year Arrangement Under the Poverty Reduction and Growth Facility, Requests for Modification of Quantitative Performance Criterion and Augmentation, and Financing Assurances Review. International Monetary Fund. 2009. p. 17. Retrieved 13 October 2013.
  20. "Authorities in Dominica reduce fuel prices". Antigua Observer Newspaper. 20 May 2020. Retrieved 5 May 2021.
  21. Thomas, Steve (5 September 2008). "Gas prices capped under $18 – lowest since July". The St. Kitts-Nevis Observer . Archived from the original on 24 May 2012.
  22. "Rotary has a new President - St. Lucia Voice News". Archived from the original on 22 December 2015.
  23. "Another service station sues SOL over fuel volume discrepancy". iWitness News.
  24. "Petrol stations in UAE go the metric route". Retrieved 5 May 2021.
  25. "End of road for imperial gallon as UAE switches to buying fuel by litre". The National. 15 December 2009. Retrieved 5 May 2021.
  26. "Gas prices at Guyoil stations remain below $1,000 mark | Caribbean Mi…". 28 June 2013. Retrieved 5 May 2021.
  27. "Petrol Prices March 2014 in Yangon, Myanmar". 5 April 2014.
  28. "The Re-Launch of Antigua And Barbuda's Metrication Programme". Diversity Global Magazine. 2013. Archived from the original on 16 January 2012. Retrieved 20 May 2013.
  29. The Council of the European Communities (9 February 2000). "Council Directive 80/181/EEC of 20 December 1979 on the approximation of the laws of the Member States relating to Unit of measurement and on the repeal of Directive 71/354/EEC" . Retrieved 7 February 2009. The legal units of measurement ... for economic, public health, public safety or administrative purposes ... litre
  30. "The Units of Measurement Regulations 1995 (Article 4)". 13 July 1995. Retrieved 1 December 2011.
  31. "Units of Measurement Directive". LACORS. 1995. Archived from the original on 24 April 2012. Retrieved 26 November 2011.
  32. "Guidance Note on the use of Metric Units of Measurement by the Public Sector" (PDF). Department of Trade and Industry. 1995. Archived from the original (PDF) on 7 February 2011. Retrieved 20 March 2017.
  33. "S.I. No. 255/1992 — European Communities (Units of Measurement) Regulations, 1992". Irish Statute Book. Office of the Attorney General. 9 September 1992. Retrieved 1 December 2011.
  34. "FAQs – Fuel Consumption Program". Transport Canada. 5 November 2008. Archived from the original on 20 May 2010. Retrieved 31 July 2018.
  35. Statutory Instrument 2001/3523 Environmental Protection - The Passenger Car (Fuel Consumption and CO2 Emissions Information) Regulations 2001 (PDF). The Stationery Office. 30 October 2001. ISBN   0-11-038743-0 . Retrieved 1 December 2011.
  36. Canada, Natural Resources (30 April 2018). "energuide-vehicles". Retrieved 21 February 2021.
  37. "Gasoline goes up eleven cents per gallon tomorrow". Samoa News. Archived from the original on 4 March 2016.
  38. Dones, Liberty (17 May 2006). "Shell pump prices up 8 cents". Saipan Tribune. Archived from the original on 30 October 2006. Retrieved 30 September 2013.
  39. "UPDATE: Gas prices down 10 cents to $4.73 for a gallon of unleaded". Pacific Daily News. Archived from the original on 30 September 2013.
  40. Blackburn, Joy (16 July 2012). "7-cent-per-gallon WAPA tax goes into effect". Virgin Islands Daily News. Archived from the original on 30 September 2013.
  41. Pesquera de Busquets, Carmen T; Barcelo, Carlos Romero (14 June 1979), Order to establish the price of half 1/2 galon [sic] of gasoline as transitory measure and that the litter [sic] should be the final metric measurement for the sale of gasoline in Puerto Rico (PDF), San Juan, Puerto Rico: Departamento de Asuntos del Consumidor, retrieved 21 May 2013
  42. "La gasolina se venderá en litros y otros productos se pesarán en kilogramos, según nuevo sistema métrico a implementarse en 2021 | Noticias de El Salvador". Noticias de El Salvador - (in Spanish). 16 December 2020. Retrieved 5 May 2021.
  43. "New Measures to Improve TCI Finances And Prioritise Spending".
  46. E. Frank Henriques, The Signet Encyclopedia of Wine, p. 298
  47. Cherry, Rona (11 October 1976). "Liquor Industry Converts to Metric System". The New York Times .
  48. "gallon, n.". Oxford English Dictionary (2 ed.). Oxford, England: Oxford University Press. 1989.
  49. "English wine gallon". Retrieved 17 June 2010.