Wikipedia

Tonne

This article is about the metric unit of mass. For other ton units, seeTon.For other uses of tonne, seeTonne (disambiguation).For other uses of "megagram", seeMegagram (geometry).
"Gigatons" redirects here. For the album by Pearl Jam, seeGigaton.

Thetonne(/tʌn/ⓘor/tɒn/;symbol:t) is a unit of mass equal to 1,000kilograms.It is anon-SI unit accepted for use with SI.It is also referred to as ametric tonin the United States to distinguish it from thenon-metric unitsof theshort ton(United States customary units) and thelong ton(British imperial units). It is equivalent to approximately 2,204.6pounds,1.102 short tons, and 0.984 long tons. The official SI unit is themegagram(Mg), a less common way to express the same amount.

Tonne
Megagram
A one-tonne (1000-kilogram) concrete block
General information
Unit ofmass
Symbolt
Mg
InSI units:1000 kg

Symbol and abbreviations

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TheBIPMsymbol for the tonne is t, adopted at the same time as the unit in 1879.[1]Its use is also official for the metric ton in the United States, having been adopted by the United StatesNational Institute of Standards and Technology(NIST).[2][3]It is a symbol, not an abbreviation, and should not be followed by aperiod.Use of lower case is significant, and use of other letter combinations can lead to ambiguity. For example, T, MT, mT, are the SI symbols for thetesla,megatesla, and millitesla, respectively, while Mt and mt are SI-compatible symbols for the megatonne (one teragram) and millitonne (one kilogram). If describingTNT equivalentunits of energy, one megatonne of TNT is equivalent to approximately 4.184petajoules.

Origin and spelling

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In English,tonneis an established spelling alternative tometric ton.[4]In the United States and United Kingdom, tonne is usually pronounced the same as ton (/tʌn/), but the final "e" can also be pronounced, i.e. "tunnie"(/ˈtʌni/).[5]In Australia, the common and recommended pronunciation is/tɒn/.[6][7]In the United States,metric tonis the name for this unit used and recommended by NIST;[2]an unqualified mention of atonalmost invariably refers to ashort tonof 2,000 lb (907.2 kg) and to a lesser extent to along tonof 2,240 lb (1,016 kg), with the termtonnerarely used in speech or writing. Both terms are acceptable inCanadian English.

Tonandtonneare both derived from aGermanicword in general use in theNorth Seaarea since theMiddle Ages(cf.Old EnglishandOld Frisiantunne,Old High GermanandMedieval Latintunna,GermanandFrenchtonne) to designate a large cask, ortun.[8]A full tun, standing about a metre high, could easily weigh a tonne. See also the common German wordde:Mülltonne(literal translation: garbagedrum).

The spellingtonnepre-dates the introduction of the SI in 1960; it has been used with this meaning in France since 1842,[9]when there were no metric prefixes for multiples of 106and above, and is now used as the standard spelling for the metric mass measurement in mostEnglish-speaking countries.[10][11][12][13]In the United States, the unit was originally referred to using theFrenchwordsmillierortonneau,[14]but these terms are now obsolete.[15]The British imperial and United States customary units are comparable to thetonneand the spelling oftonin English is the same, though they differ in mass.

Conversions

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One tonne is equivalent to:

  • Inkilograms:1000 kilograms (kg)by definition.[16]
  • Ingrams:1000000grams (g)or 1 megagram (Mg). Megagram is the corresponding official SI unit with the same mass. Mg is distinct from mg, milligram.
  • Inpounds:Exactly⁠1000/0.453 592 37⁠pounds (lb) by definition of the pound,[17]or approximately2204.622622lb.[18]
  • Inshort tons:Exactly⁠1/0.907 184 74⁠short tons (tn), or approximately1.102311311tn.
    • One short ton is exactly0.90718474t.[19]
  • Inlong tons:Exactly⁠1/1.016 046 9088⁠long tons (LT), or approximately0.9842065276LT.
    • One long ton is exactly1.0160469088t.[19]

A tonne is the mass of onecubic metreof pure water at 4 °C (39 °F).[a]

Derived units

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As a non-SI unit, the use of SI metric prefixes with the tonne does not fall within the SI standard. For multiples of the tonne, it is more usual to speak of thousands or millions of tonnes. Kilotonne, megatonne, and gigatonne are more usually used for the energy of nuclear explosions and other events inequivalent mass of TNT,often loosely as approximate figures. When used in this context, there is little need to distinguish between metric and other tons, and the unit is spelled either astonortonnewith the relevant prefix attached.[b]

Tonnes Grams Equivalents*
Name Symbol Name Symbol Tonnes (t) Short Tons (tn)† Long Tons (LT)†
tonne t megagram Mg 1 t 1.1023 tn 0.98421LT
kilotonne ktǂ gigagram Gg 1,000 t 1102.3tn 984.21 LT
megatonne Mt teragram Tg 1,000,000 t 1.1023 million tn 984210LT
gigatonne Gt petagram Pg 1,000,000,000 t 1.1023 billion tn 984.21 million LT

*The equivalent units columns use theshort scalelarge-number naming system currently used in most English-language countries, e.g. 1 billion = 1000 million =1000000000.
†Values in the equivalent short and long tons columns areroundedto fivesignificant figures.SeeConversionsfor exact values.
ǂThough non-standard, the symbol "kt" is also used (instead of the standard symbol "kn" ) forknot,a unit of speed foraircraftandwatercraft.The standard meaning of the symbol kt is for kilotonne.

Alternative usages

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Metric ton units

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Ametric ton unit(mtu) can mean 10 kg (22 lb) within metal trading, particularly within the United States. It traditionally referred to a metric ton of ore containing 1% (i.e. 10 kg) of metal.[20][21] The following excerpt from a mining geology textbook describes its usage in the particular case of tungsten:

Tungsten concentrates are usually traded in metric tonne units (originally designating one tonne of ore containing 1% of WO3,today used to measure WO3quantities in 10 kg units. One metric tonne unit (mtu) of tungsten (VI) contains 7.93 kilograms of tungsten.

— Walter L Pohl,Economic Geology: Principles and Practices,English edition, 2011, p 183.

In the case ofuranium,MTUis sometimes used in the sense ofmetric ton of uranium(1,000 kg (2,200 lb)).[22][23][24][25]

Use of mass as proxy for energy

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Main article:TNT equivalent

Thetonne oftrinitrotoluene(TNT)is used as a proxy for energy, usually of explosions (TNT is a commonhigh explosive). Prefixes are used: kiloton(ne), megaton(ne), gigaton(ne), especially for expressingnuclear weapon yield,based on aspecific combustion energyof TNT of about 4.2MJ/kg(or onethermochemical caloriepermilligram). Hence, 1 t TNT =approx.4.2GJ,1ktTNT = approx. 4.2TJ,1 Mt TNT = approx. 4.2PJ.

The SI unit of energy is thejoule.One tonne of TNT is approximately equivalent to 4.2 gigajoules.

In thepetroleum industrythetonne of oil equivalent(toe) is aunit of energy:the amount of energy released by burning one tonne ofcrude oil,approximately 42 GJ. There are several slightly different definitions. This is ten times as much as a tonne of TNT because atmospheric oxygen is used.

Unit of force

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Like thegramand the kilogram, the tonne gave rise to a (now obsolete) force unit of the same name, the tonne-force, equivalent to about 9.8kilonewtons.The unit is also often called simply "tonne" or "metric ton" without identifying it as a unit of force. In contrast to the tonne as a mass unit, the tonne-force is not accepted for use with SI.

See also

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Notes and references

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Notes
  1. ^To within 0.003%.
  2. ^The Oxford English Dictionary 2nd ed. gives both megaton and megatonne and adds "The unit may be calculated in either imperial or metric tons; the form megatonne generally implies the metric unit". The use for energy is the first definition; use for mass or weight is the third definition.
Citations
  1. ^Table 6Archived2009-10-01 at theWayback Machine.BIPM. Retrieved on 2011-07-10.
  2. ^abMetric System of Measurement: Interpretation of the International System of Units for the United StatesArchived2008-04-09 at theWayback Machine(PDF). See corrections in the Errata section of[1]Archived2008-04-18 at theWayback Machine.
  3. ^NISTSpecial Publication 330, 2019 editionstates "The name of the unit with symbol t and defined according to 1 t = 103kg is called 'metric ton' rather than 'tonne.' ".
  4. ^"tonne, n".OED.Retrieved6 August2021.
  5. ^The Oxford English dictionary 2nd ed. lists both /tʌn/ and /ˈtʌni/
  6. ^Macquarie Dictionary(fifth ed.). Sydney: Macquarie Dictionary Publishers Pty Ltd. 2009.
  7. ^"How To Pronounce Metrics Units (advertisement by Australian Metric Conversion Board)".The Age.1972-11-21. p. 14.Retrieved2021-11-01.
  8. ^Harper, Douglas."tonne".Online Etymology Dictionary.
  9. ^"Recherche d'un mot".atilf.atilf.fr.
  10. ^"Guidance Note on the use of Metric Units of Measurement by the Public Sector"(PDF).National Measurement Office. 2007. Archived fromthe original(PDF)on 2011-02-07.Retrieved2010-02-13."Tonne" is listed under "The Principal Metric Units of Measurement" on p. 7.
  11. ^"National Measurement Regulations 1999 |".Australian Government. 1999.Retrieved2010-02-13."Tonne" is listed under Schedule 1, Part 3 as a non-SI unit of measurement used with SI units of measurement.
  12. ^"Appendix 4: Units of Measurement and Conversion Factors".MAF (Ministry of Agriculture and Forestry (New Zealand)).Retrieved2010-02-13.
  13. ^"Canada Gazette".Government of Canada. 1998–2007. Archived fromthe originalon 2011-07-06.Retrieved2010-02-13.The Corporation shall pay to producers selling and delivering wheat produced in the designated area to the Corporation the following sums certain per tonne basis...
  14. ^Act of July 28, 1866, codified in15 U.S.C.§ 205
  15. ^"Metric System of Measurement: Interpretation of the International System of Units for the United States"(PDF).Federal Register.63(144): 40338. July 28, 1998. 63 FR 40333. Archived fromthe original(PDF)on October 15, 2011.
  16. ^Le Système international d’unités[The International System of Units](PDF)(in French and English) (9th ed.), International Bureau of Weights and Measures, 2019,ISBN978-92-822-2272-0
  17. ^Barbrow, L.E.; Judson, L.V. (1976).Weights and measures standards of the United States – A brief history.Archived fromthe originalon 2008-05-11.
  18. ^United States National Bureau of Standards (1959-06-25)."Notices" Refinement of values for the yard and the pound ""(PDF).Retrieved2006-08-12.
  19. ^abNational Institute of Standards and Technology.Butcher, Tina; Crown, Linda; Harshman, Rick; Williams, Juana, eds. (October 2013)."Appendix C – General Tables of Units of Measurement"(PDF).Specifications, Tolerances, and Other Technical Requirements for Weighing and Measuring Devices.NIST Handbook. Vol. 44 (2014 ed.). Washington, D.C.: U.S. Department of Commerce, Technology Administration, National Institute of Standards and Technology. p. C-13.ISSN0271-4027.OCLC58927093.Retrieved10 December2013.
  20. ^"Platt's Metals Guide to Specifications – Conversion Tables".8 September 2008. Archived from the original on 8 September 2008.{{cite web}}:CS1 maint: bot: original URL status unknown (link)
  21. ^How Many? A Dictionary of Units of MeasurementArchived2011-09-04 at theWayback Machine.Unc.edu. Retrieved on 2011-07-10.
  22. ^Reference.Pdf.(PDF). Retrieved on 2011-07-10.
  23. ^"GlossaryArchived2010-03-14 at theWayback Machine".(June 2000).Disposition of Surplus Hanford Site Uranium, Hanford Site, Richland, Washington.US Department of Energy.
  24. ^"AcronymsArchived2013-03-12 at theWayback Machine".Y-12 National Security Complex.
  25. ^NRC Collection of Abbreviations (NUREG-0544, Rev. 4), United States Nuclear Regulatory Commission.Nrc.gov (2011-03-13). Retrieved on 2011-07-10.
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