Gallon Explained

gallon
Quantity:Volume
Symbol:gal
Units Imp1:SI units
Inunits Imp1:1sigfig=6NaNsigfig=6
Units Imp2:US customary units
Inunits Imp2:≈1sigfig=7NaNsigfig=7
Units Imp3:US customary units
Inunits Imp3:≈1sigfig=7NaNsigfig=7
Units Us1:SI units
Inunits Us1:1sigfig=10NaNsigfig=10
Units Us2:Imperial units
Inunits Us2:≈1sigfig=7NaNsigfig=7
Units Us3:Imperial units
Inunits Us3:1sigfig=3NaNsigfig=3
Units Us4:US dry gallon
Inunits Us4:≈1sigfig=6NaNsigfig=6

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

There are two pints in a quart and four quarts in a gallon. Different sizes of pints account for the different sizes of the imperial and US gallons.

The IEEE standard symbol for both US (liquid) and imperial gallon is gal,[2] not to be confused with the gal (symbol: Gal), a CGS unit of acceleration.

Definitions

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.[3]

Imperial gallon

The British imperial gallon (frequently called simply "gallon") is defined as exactly 4.54609 dm3 (4.54609 litres).[4] It is used in some Commonwealth countries, and until 1976 was defined as the volume of water at [5] [6] whose mass is 10lb. There are four imperial quarts in a gallon, two imperial pints in a quart, and there are 20 imperial fluid ounces in an imperial pint,[4] yielding 160 fluid ounces in an imperial gallon.

US liquid gallon

The US liquid gallon (frequently called simply "gallon") is legally defined as 231 cubic inches, which is exactly 231in3.[7] [8] A US liquid gallon can contain about 3.785kg (08.344lb) of water at, and is about 16.7% less 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 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[9] and alcoholic beverages[10] are both referenced to in government regulations.

US dry gallon

See main article: Dry gallon. Since the dry measure is one-eighth of a US Winchester bushel of cubic inches, it is equal to exactly 268.8025 cubic inches, which is .[11] 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.[12]

Worldwide usage

Imperial gallon

As of 2021, the imperial gallon continues to be used as the standard petrol unit on 10 Caribbean island groups, consisting of:

All 12 of the Caribbean islands use miles per hour for speed limits signage, and drive on the left side of the road.

The United Arab Emirates ceased selling petrol by the imperial gallon in 2010 and switched to the litre, with Guyana following suit in 2013.[26] [27] [28] In 2014, Myanmar switched from the imperial gallon to the litre.[29]

Antigua and Barbuda has proposed switching to selling petrol by litres since 2015.[30] [19]

In the European Union the gallon was removed from the list of legally defined primary units of measure catalogue in the EU directive 80/181/EEC for trading and official purposes, effective from 31 December 1994. Under the directive the gallon could still be used, but only as a supplementary or secondary unit.[31]

As a result of the EU directive Ireland and the United Kingdom passed 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 31 December 1993, and 30 September 1995 respectively.[32] [33] [34] [35] 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. However, barrels and large containers of beer, oil and other fluids are commonly measured in multiples of an imperial gallon.

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.[36] [37] [38]

US liquid gallon

Other than the United States, petrol is sold by the US gallon in 13 other countries, and one US territory:

The latest country to cease using the gallon is El Salvador in June 2021.[44]

The Imperial and US liquid gallon

Both the US gallon and imperial gallon are used in the Turks and Caicos Islands (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))[45] and the Bahamas.[46] [47]

Legacy

In some parts of the Middle East, such as the United Arab Emirates and Bahrain, 18.9-litre water cooler bottles are marketed as five-gallon bottles.[48]

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 (not in customary use outside the US), 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 of an imperial pint, or of an imperial gallon, while a US fluid ounce is of a US pint, or 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".[49] [50]

History

The term derives most immediately from galun, galon in Old Norman French,[51] but the usage was common in several languages, for example French, Old (842-ca.1400);: jale in Old French and English, Old (ca.450-1100);: gęllet (bowl) in Old English. This suggests a common origin in Romance Latin, but the ultimate source of the word is unknown.[52]

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 inches in diameter and 8 inches in depth, which made the bushel . The bushel was later defined to be 2150.42 cubic inches exactly, thus making its gallon exactly ; 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. . It was redefined during the reign of Queen Anne in 1706 as 231 cubic inches exactly, the earlier definition with approximated to .

\pi r^2h \approx \frac\times\left (\frac \right)^2\times6 ~ \mathrm = 231 ~ \mathrm^3.

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 was actually in use, requiring this statute; the 231 cubic inch gallon 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 (14.7345 pound-force per square inch) and at a temperature of .

In 1963, this definition was refined as the space occupied by 10 pounds of distilled water of density weighed in air of density against weights of density (the original "brass" was refined as the densities of brass alloys vary depending on metallurgical composition), which was calculated as to ten significant figures.[5]

The precise definition of exactly cubic decimetres (also, ≈ ) came after the litre was redefined in 1964. This was adopted shortly afterwards in Canada, and adopted in 1976 in the United Kingdom.[5]

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
VolumeDefinitionInverted
volume
(gal/cu ft)		Weight as
water at
(pounds/gal)		Cylindrical approximation
(cu in)(dm3)Diameter
(in)		Height
(in)		Volume rel.
error (%)
Current gallons
231 Statute of 5 Queen Anne
UK wine gallon
Standard US gallon		7.48 8.337 6 0.04
268.8025Winchester, statute of 13 & 14 William III
Corn gallon
US dry gallon		6.43 9.7118.5 1
≈ 277.41944.54609Standard imperial gallon≈ 6.23 1011
Historic gallons
216 (Roman unciae)≈ 3.53961Roman congius8 7.85 11 0.01
224 ≈ 3.67070Preserved at the Guildhall, London (old UK wine gallon)7.71 8.099 3.5 0.6
264.8 ≈ 4.33929Ancient Rumford quart (1228)6.53 9.577.5 6 0.1
265.5 ≈ 4.35077Exchequer (Henry VII, 1497, with rim)6.51 9.5913 2 0.01
266.25 ≈ 4.36306Ancient Rumford (1228)        
271 ≈ 4.44089Exchequer (1601, E.) (old corn gallon)6.38 9.794.5 17 0.23
272 ≈ 4.45728Corn gallon (1688)        
≈ 277.2026≈ 4.54254Statute of 12 Anne (coal gallon) = corn gallons6.23 10     
≈ 277.274 ≈ 4.54370 Imperial gallon, as originally determined in 18246.23 10     
≈ 277.4195Imperial gallon as re-determined in 1895 and defined in 1963≈ 6.23 10     
278 ≈ 4.55560Exchequer (Henry VII, with copper rim)6.21 10.04     
278.4 ≈ 4.56216Exchequer (1601 and 1602 pints)6.21 10.06     
280 ≈ 4.58838Exchequer (1601 quart)6.17 10.1     
282 ≈ 4.62115Treasury (beer and ale gallon pre-1824)6.13 10.2     

Notes and References

  1. Book: Thompson . E Ambler . Taylor . Barry N . 2008 . Guide for the use of the International System of Units (SI) . National Institute of Standards and Technology . 10.6028/nist.sp.811e2008 . free.
  2. IEEE Std 260.1-2014
  3. Web site: Ricketts. Carl. Capacity Measures of the British Isles. 6 September 2016. 7 October 2016. https://web.archive.org/web/20161007001010/http://www.pewterbank.com/Measure_for_Measure...by_Carl_Ricketts....18.pdf. dead.
  4. Web site: Weights and Measures Act 1985, chapter 72, schedule 1. legislation.gov.uk. The National Archives on behalf of HM Government. 7 June 2019.
  5. Book: BS 350:Part 1:1974 Conversion factors and tables Part 1. Basis of tables. Conversion factors. 1983. British Standards Institution. Foreword. AMD 4153. 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)....
  6. Book: BS 350:Part 1:1974 Conversion factors and tables Part 1. Basis of tables. Conversion factors. 1974. British Standards Institution. 10. prior to Amendment No.1 1983. 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..
  7. NIST Handbook 44 - 2012 Edition Appendix C "General Tables of Units of Measurement". NIST . 26 October 2012. C-5.
  8. Book: Uniform Laws and Regulations in the areas of legal metrology and engine fuel quality. 2011. US Department of Commerce, National Institute of Standards and Technology. 9–13, 69. https://web.archive.org/web/20120927010401/http://www.nist.gov/pml/wmd/pubs/upload/HB130-11-final.pdf . 2012-09-27 . live.
  9. Web site: State of New Hampshire Dept of Weights and Measure. https://web.archive.org/web/20120413013031/http://www.nh.gov/agric/news/documents/weights-fuel-temperature.pdf. dead. 13 April 2012.
  10. Web site: 27 CFR section 5.21. https://web.archive.org/web/20131019135845/http://www.gpo.gov/fdsys/pkg/CFR-2011-title27-vol1/pdf/CFR-2011-title27-vol1-sec5-21.pdf . 2013-10-19 . live. Gpo.gov. 29 January 2022.
  11. Web site: US Dry Conversion Calculator. High accuracy calculation for life or science.. en. 2019-10-24. 24 October 2019. https://web.archive.org/web/20191024225749/https://keisan.casio.com/exec/system/1344320515. dead.
  12. https://www.law.cornell.edu/uscode/search/display.html?terms=unit%20measure&url=/uscode/html/uscode15/usc_sec_15_00000205----000-notes.html Authorized tables
  13. Web site: 19 October 2012. Anguilla Renewable Energy Integration Project Final Report. https://web.archive.org/web/20131014175039/http://cdkn.org/wp-content/uploads/2012/08/Anguilla-RE-Integration-Final-Report-121019.pdf . 2013-10-14 . live. 13 October 2013. Anguilla RE Integration Final Report. Government of Anguilla Ministry of Infrastructure, Communications, Utilities, and Housing (MICUH). 104. 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..
  14. Web site: Walker. William. 5 September 2012. Biwater project draws scrutiny. https://web.archive.org/web/20131002140602/http://www.bvibeacon.com/2/index.php?option=com_content&view=article&id=2487:biwater-project-draws-scrutiny&catid=491:commentary-sept-6-2012. 2013-10-02. 2013-09-30.
  15. Web site: Statement By Premier Fahie In One-On-One Press Conference - Update On Current Matters Government of the Virgin Islands . 2022-12-16 . bvi.gov.vg.
  16. News: Wilson. Stuart. 9 May 2013. Fuel costs driven by factors. Cayman Compass. 30 September 2013. 22 December 2015. https://web.archive.org/web/20151222131450/http://www.compasscayman.com/caycompass/2013/05/09/Fuel-costs-driven-by-factors/. dead.
  17. News: 30 November 2012. Petrol price increases, diesel decreases, cost of living goes up. The Montserrat Reporter. 30 September 2013. 3 October 2022. https://web.archive.org/web/20221003154555/http://www.themontserratreporter.com/gasoline-price-increases-diesel-decreases-cost-of-living-goes-up/. dead.
  18. News: Htin Lynn Aung. 22 September 2017. Fuel prices on the rise. The Myanmar Times. 18 January 2018. 18 January 2018. https://web.archive.org/web/20180118064732/https://www.mmtimes.com/news/fuel-prices-rise.html. dead.
  19. Web site: Government of Antigua and Barbuda. 2021-05-05. ab.gov.ag.
  20. Web site: 10 May 2011. Photo of the day: Up and up it goes. Dominica News Online. 30 September 2013. 21 February 2018. https://web.archive.org/web/20180221103436/http://dominicanewsonline.com/news/homepage/features/photo-of-the-day/photo-of-the-day-up-and-up-it-goes/. dead.
  21. Book: 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. 17. 13 October 2013.
  22. Web site: 2020-05-20. Authorities in Dominica reduce fuel prices. 2021-05-05. Antigua Observer Newspaper. en-CA.
  23. Web site: Thomas. Steve. 5 September 2008. Gas prices capped under $18 – lowest since July. dead. https://web.archive.org/web/20120524184004/http://thestkittsnevisobserver.com/2008/09/05/news21.html. 24 May 2012. The St. Kitts-Nevis Observer. dmy.
  24. Web site: Rotary has a new President - St. Lucia Voice News. dead. https://web.archive.org/web/20151222145630/http://www.thevoiceslu.com/local_news/2013/july/09_07_13/Rotary.htm. 22 December 2015. dmy.
  25. Web site: Another service station sues SOL over fuel volume discrepancy. iWitness News. 26 April 2012 .
  26. Web site: Petrol stations in UAE go the metric route. 2021-05-05. gulfnews.com. en.
  27. Web site: 2009-12-15. End of road for imperial gallon as UAE switches to buying fuel by litre. 2021-05-05. The National. en.
  28. Web site: 2013-06-28. Gas prices at Guyoil stations remain below $1,000 mark Caribbean Mi…. 2021-05-05. Archive.is. 28 June 2013. https://archive.today/20130628202944/http://www.caribmillers.com/content/gas-prices-guyoil-stations-remain-below-1000-mark. dead.
  29. Web site: Petrol Prices March 2014 in Yangon, Myanmar. Oilseedcrops.org. 5 April 2014.
  30. Web site: 2013. The Re-Launch of Antigua And Barbuda's Metrication Programme. dead. https://web.archive.org/web/20120116182201/http://www.cbji.com/makingnews.aspx?id=692. 16 January 2012. 20 May 2013. Diversity Global Magazine.
  31. Web site: 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. 7 February 2009. The legal units of measurement ... for economic, public health, public safety or administrative purposes ... litre.
  32. Web site: 13 July 1995. The Units of Measurement Regulations 1995 (Article 4). 1 December 2011.
  33. Web site: 1995. Units of Measurement Directive. dead. https://web.archive.org/web/20120424231200/http://www.lacors.gov.uk/lacors/ContentDetails.aspx?id=2515. 24 April 2012. 26 November 2011. LACORS. dmy.
  34. Web site: 1995. Guidance Note on the use of Metric Units of Measurement by the Public Sector. dead. http://webarchive.nationalarchives.gov.uk/20110207120946/http://www.nmo.bis.gov.uk/Docs/Legislation/Units%20of%20Measurement/Gnotes%20for%20public%20sector%20on%20use%20of%20metric.pdf. 7 February 2011. 20 March 2017. Department of Trade and Industry. dmy.
  35. Web site: 9 September 1992. S.I. No. 255/1992 — European Communities (Units of Measurement) Regulations, 1992.. 1 December 2011. Irish Statute Book. Office of the Attorney General.
  36. Web site: 5 November 2008. FAQs – Fuel Consumption Program. live. https://web.archive.org/web/20100520103922/http://www.tc.gc.ca/eng/programs/environment-fcp-faq-139.htm. 20 May 2010. 31 July 2018. Transport Canada. dmy-all.
  37. Book: Statutory Instrument 2001/3523 Environmental Protection - The Passenger Car (Fuel Consumption and CO2 Emissions Information) Regulations 2001. https://web.archive.org/web/20101218054954/http://www.legislation.gov.uk/uksi/2001/3523/pdfs/uksi_20013523_en.pdf . 2010-12-18 . live. 30 October 2001. The Stationery Office. 0-11-038743-0. 1 December 2011.
  38. Web site: Canada. Natural Resources. 2018-04-30. energuide-vehicles. 2021-02-21. Nrcan.gc.ca.
  39. Web site: June 10, 2020 . Liberia: Senate Imposes US$0.30 Tax on Each Gallon of Petroleum Product. .
  40. Web site: Gasoline goes up eleven cents per gallon tomorrow . Samoa News . dead . https://web.archive.org/web/20160304201034/http://www.samoanews.com/?q=node%2F76479 . 4 March 2016 .
  41. Web site: Shell pump prices up 8 cents . Saipan Tribune . Liberty . Dones . 17 May 2006 . 30 September 2013 . dead . https://web.archive.org/web/20061030231121/http://www.saipantribune.com/newsstory.aspx?newsID=57572&cat=1 . 30 October 2006 . dmy-all .
  42. Web site: UPDATE: Gas prices down 10 cents to $4.73 for a gallon of unleaded . https://archive.today/20130930053836/http://www.guampdn.com/article/20130808/NEWS01/130808005/UPDATE-Gas-prices-down-10-cents-4-73-gallon-unleaded . dead . 2013-09-30 . Pacific Daily News .
  43. News: 7-cent-per-gallon WAPA tax goes into effect . https://archive.today/20130930053844/http://virginislandsdailynews.com/news/7-cent-per-gallon-wapa-tax-goes-into-effect-1.1344082 . dead . 30 September 2013 . Joy . Blackburn . 16 July 2012 . Virgin Islands Daily News . dmy .
  44. Web site: 2020-12-16. 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. 2021-05-05. Noticias de El Salvador - elsalvador.com. es.
  45. Web site: New Measures to Improve TCI Finances And Prioritise Spending. TheBahamasWeekly.com.
  46. Web site: OFFICIAL GAZETTE THE BAHAMAS PUBLISHED BY AUTHORITY : NASSAU . https://web.archive.org/web/20210602214208/http://laws.bahamas.gov.bs/cms/images/LEGISLATION/SUBORDINATE/2014/2014-0005/ProtectionofRevenueImpostsVariationAmendmentOrder2014_1.pdf . 2021-06-02 . live. 12 February 2014 . Laws.bahamas.gov.bs. 29 January 2022.
  47. Web site: Weights and Measures . Statute Law of the Bahamas . 1 June 2021 . dead . https://web.archive.org/web/20210602215910/https://www.bbsq.bs/en/files/acts-and-regulations/1-weights-and-measures-act/file . 2 June 2021.
  48. Web site: AL MANHAL DRINKING WATER 5 GALLON (18.9 LITERS) BOTTLE .
  49. E. Frank Henriques, The Signet Encyclopedia of Wine, p. 298
  50. News: Liquor Industry Converts to Metric System. 11 October 1976. Rona. Cherry. The New York Times.
  51. Gallon . 11 . 421.
  52. Book: Oxford English Dictionary. 2. 1989. Oxford University Press. Oxford, England. gallon, n..
  53. Encyclopedia: English wine gallon. Sizes.com. 2010-06-17.

This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Gallon".

Except where otherwise indicated, Everything.Explained.Today is © Copyright 2009-2024, A B Cryer, All Rights Reserved. Cookie policy.