From Wikipedia, the free encyclopedia
Jump to: navigation, search
WikiProject Measurement (Rated C-class)
WikiProject icon This article is within the scope of WikiProject Measurement, a collaborative effort to improve the coverage of Measurement on Wikipedia. If you would like to participate, please visit the project page, where you can join the discussion and see a list of open tasks.
C-Class article C  This article has been rated as C-Class on the project's quality scale.
Checklist icon
 ???  This article has not yet received a rating on the project's importance scale.


The first paragraph of this "explanatory" article is a confusing mass of claptrap and trivial nonsense. -- Brothernight (talk) 05:12, 14 May 2011 (UTC)

Agree. It is contradictory, first implying very strongly that it is an SI unit with "(SI unit symbol: t)", and then stating that it isn't an SI unit with "It is a non-SI unit [...]".
—DIV ( (talk) 03:18, 29 November 2012 (UTC))
From what you said, it would appear that way, but if you hadn't truncated to sentence where you did that wouldn't be the case. It does not say "It is a non-SI unit", but "It is a non-SI unit accepted for use with SI". In other words, it is not an official SI unit, but its use is accepted within the SI system (similar to the minute, the degree and many other units; see non-SI units mentioned in the SI). Is it potentially confusing? Yes. Is it contradictory? No.
Also note when that post was made - May 2011. As such, it is not referring to the current lead, but to this version: [1].
Alphathon /'æɫ.fə.θɒn/ (talk) 16:23, 2 December 2012 (UTC)

word origins[edit]

The naming of this unit was far from original because SI advocates derived the name of their unit from the already well established ton and added an '-ne' suffix to differentiate between the SI tonne and non-metric ton. The tonne is also less formally called metric ton but this name is deprecated since it mixes metric and non-metric terms.

This wasn't done by "SI advocates"; the names ton and tonne existed long before there was an SI, which was only introduced in 1960.

It wasn't the adding of an -ne to the English word for this distinguishing purpose. Rather, it was a direct borrowing of the French word. A French word which dates back to even before there was any metric system, let alone the modern version called the International System of Units.

In French, of course, "tonne" is just as ambiguous as "ton" is in English. What do you suppose an unidentified "tonne" would have been in Quebec 50 years ago, for example? Most likely a tonne courte, or 2000 English pounds, unless it was in shipping where it would likely be the tonne forte of 2240 lb.

I'm no expert in French, but I think it would be a pretty safe assumption that today (though not necessarily in the past), wherever French is spoken or written, if tonne is used without any other identifying adjective, it is the tonne mètrique.

In English, "tonne" is somewhat less ambiguous than in French. Nonetheless, the terms "short tonne" and "long tonne" are used, rarely. Furthermore, many are careful to specifically identify the units as "metric tonnes"; Google
"metric tonne" 37,200 hits
"metric tonnes" 149,000 hits

Gene Nygaard 14:09, 16 Dec 2004 (UTC)

To complicate matters, the French « tonne » also designates a large liquid container (of which the barrel, « tonneau » is a diminutive), more or less the equivalent of the English tun.
Urhixidur 11:25, 2005 Jun 23 (UTC)

I don't get the part with celtic origin. I'm no linguist, but what word in celtic should it derive from through what transformations? Tonne is also used in German as well for the metric ton of a thousand kilogram as for the big barrel. If it is a word we derived from french, I would be interested what theory of celtic origin exists. As it is, the mention of a possible celtic origin is not helpful but rather confusive. 09:11, 6 September 2007 (UTC)

The Celtic reference is no longer in the article (and the section on the origin of the word is complete enough as it now stands IMHO). But, just for the record, it is possible that the word "tun" in the wine-cask sense is derived from Celtic (cf. Middle Irish tunna = skin, hide), given that wine was formerly transported in skins. -- Picapica (talk) 08:54, 13 March 2011 (UTC)


"ton of TNT or tonne of Trinitrotoluene is a unit of energy based on the tonne, assuming 1000 small (thermochemical) calories per gram (4.184 kJ/g) and thus a tonne of TNT is 4.184 GJ. This unit is also not acceptable for use with SI."

This argument is pretty much meaningless, because those who speak (kilo)ton TNT have the nukes and so they don't need to care a damn about SI or customary units. It's hard to argue with someone who has the bomb ...

i've seen not acceptable for use with SI in various places on wikipedia. I suspect "acceptable for use with SI" has a specific technical and/or regulatory meaning can anyone confirm?
There are three or four different classes of units which are acceptable for SI; some of those units are only "currently" (BIPM) or "temporarily" (NIST) acceptable.
Gene Nygaard 10:04, 23 Jun 2005 (UTC)


surely the tonne is a measurement of mass and not weight as is stated in the first line of the wiki entry ?

Surely you are confused. Both of those words are ambiguous words, with several different meanings. Much of the time they mean the very same thing. Quite properly and legitimately, in usages well justified in history, in linguistics, and in the law. Gene Nygaard (talk) 03:04, 31 March 2008 (UTC)
Surely, the first user was not confused. The words "mass" and "weight" are often used interchangeably; this does not mean that they "properly and legitimately" have the same meaning. If I have a tonne of lead on Earth, and I move it to the Moon, is it still a tonne of lead? If the answer is yes, then the tonne is a unit of mass. If the answer is no, then the tonne is a unit of weight. Your allusions to history, linguistics, and law are obsolete. The vast majority of humanity's history and language took shape before we had the ability to leave Earth; legal codes adopted since the "space race" still generally assume an Earthbound jurisdiction where the weight/mass distinction is mostly irrelevant. Colonizing other bodies in the solar system (or beyond) will inevitably require that lawyers pay more attention in science class. Cheers. (talk) 12:53, 31 March 2008 (UTC)
We have been for over a thousand years, since the word first entered Old English, been using weight to mean the quantity measured with a balance. That quantity is mass, not force. That is what weight always means—the quantity called "mass" in physics jargon—in any usage in commerce for the weight of goods. That is what is properly required by our laws. Fortunately, nobody ever gave your confused physics teachers (are you now one of them yourself?) any say-so in what this weight means.
There is no place anywhere where it is legal to buy and sell goods by the newton. We do it by the kilogram, or in some places by the pound, which has been legally defined as an exact fraction of a kilogram in the United States for 115 years, and throughout the world for the last half-century as exactly 0.45359237 kg. This should not change if we ever buy and sell goods on the Moon or Mars or whatever; it is quite proper and legitimate, as I said. The prices might be different because of the law of supply and demand, transportation costs, etc.—but the units in which that weight is measured will remain the same. But you already know that; you talked about a "tonne" (a unit acceptable for use with SI when and only when it is used as a unit of mass) of lead. It is a "unit of weight"; but while the tonne-force and the related kilogram-force were the primary units used to measure thrust of rockets in the Soviet Union until almost the time of its breakup, and which are still sometimes used today for that purpose by China and the European Space Agency, those are not the units which are acceptable for use with SI.
And it isn't really all that irrelevant. A variation of more than one part in 140 in the acceleration of free fall at various points on the surface of the Earth can be very significant, especially if you are talking about a 401.23 troy ounce bar of platinum. But even in more mundane applications, our scales are calibrated and tested and certified on the basis of their accuracy in measuring mass, by testing them in the very place in which they are used, not on their accuracy in measuring force. For a classical two-pan balance, of course, the adjustments occur naturally; in normal usage, there isn't any significant variation in the acceleration of gravity affecting one side of the balance as compared to the other, so the effect of those variations are naturally canceled out. Those mass-measuring balances, of course, are the only weighing instruments mankind ever used for the first 7,500 years or so that they have been weighing things; even as recently as 200 years ago, you still could not buy any scale that wasn't a balance. They didn't exist.
That is what weight always means, whenever anybody talks about
  1. net weight (not a physics term)
  2. troy weight (Unlike their avoirdupois cousins and unlike grams and kilograms, troy ounces have never spawned a unit of force of the same name. They are always, and always have been, units of mass.)
  3. atomic weight (terminology in science)
  4. molecular weight (no bullshit about this being obsolete, please—13,400,000 Google hits, including hundreds of examples right here on Wikipedia, say otherwise)
  5. formula weight
  6. dry weight
  7. the pennyweight is always a unit of mass, never a unit of force
  8. the hundredweight is always a unit of mass, even if you think hundred is written in digits as "112"
  9. flyweight, bantamweight, cruiserweight, and the like
  10. curb weight (even if you spell it kerb weight)
  11. and many, many more
Those are all measurements of mass, not of force. All measured, and properly so, in kilograms or pounds, not in newtons or kilograms force or poundals or pounds-force. Whenever we talk about body weight of humans in the medical sciences, or of other animals as well in the sciences of zoology and paleontology, those are measurements of mass, not of force. It is only in the confused usage of physics textbooks and science museum exhibits where these are treated as measurements of force, but that misusage has so forcefully been put out to the public that many people really believe that their weight would change if they went to the moon. But it doesn't change in the language of NASA's doctors having the astronauts weigh themselves in space; they use the word weight with the same meaning used by their earthbound counterparts.
I don't why you are taking a "tonne of lead" to the moon. Why are you trying to invent something, when we can look at some things which actually happened? When NASA tells us on their "Selected Mission Weights" page that the "weight" of the Apollo 11 Lunar Module at liftoff of its ascent stage was "10,776.6 lbs.", just what the hell do you suppose that means?[2]
  • What was its mass?
  • How much force was it exerting due to gravity?
Enlighten us with your answers to those questions, please. In SI units if you like, or any other units you choose; but since this article is about the metric ton, maybe you could convert those two answers to metric tons and metric tons force, respectively. Gene Nygaard (talk) 09:05, 1 April 2008 (UTC)
Your comments are instructive, and I concede that some of my reasoning may have been misinformed. However, I would like to offer instruction of my own and also to point out that regardless of the correctness of my reasoning, the Bureau International des Poids et Mesures defines both "kilogram" and "tonne" as units of mass. I am inclined to assume, correctly or not, that they make the distinction for a reason (the distinction appears to be explained in a document my current web filter blocks, curse it... do a search on for "weight"). Therefore, the first user was surely not confused. (talk) 13:23, 1 April 2008 (UTC)
You are closer now. But what I was objecting to in what the firat poster here is is not the tonne is a "measurement of mass", but rather the "not of weight" part. It was a non sequitur; one does not follow from the other. And like I said, it is only the mass unit which is declared to be acceptable for use with SI; the same is true for the kilogram of course, but we have hundreds of articles on Wikipedia using the formerly (pre-1960) acceptable kilograms-force.
Note further that when tonnes-force are used (just look at the "what links here" in the redirects from tonne-force and tonnes-force), it is almost always used for something that is never called "weight" in anybody's book. For some different kind of force. (To get to those redirect pages, click on the link at "redirected from" at the top of the page when you get there through the redirect, then click on What links here.) So calling it (or the kilogram-force or the pound-force) a "unit of weight" would be objectionable for an entirely different reason; while they might occasionally be used for "weight" in its "force due to gravity meaning", they are most often used for entirely different kinds of force, for quantities that nobody ever calls "weight", such as thrust of a rocket engine or tension of a bicycle spoke. Gene Nygaard (talk) 14:08, 1 April 2008 (UTC)
Aha! Thank you for clarifying the matter. On a not-quite-related topic, can you tell me whether "tonne" is a homophone with "ton"? I'm not sure that I've ever heard any term used orally except "metric ton." (talk) 14:26, 1 April 2008 (UTC)
Sometimes yes, sometimes no. I'm in the U.S. too, but I've heard it about three different ways on Canadian radio and television. I'm no good at indicating what those pronunciations are, however--one is sort of like the first syllable of "tawny" as I pronounce it. Gene Nygaard (talk) 15:47, 1 April 2008 (UTC)


From the article:

The proper SI unit for a tonne would be a "kilokilogram" (the kilogram is the basic unit, not the gram), but this term is never used in practice.

This sounds fishy to me. A gram is a gram, not a "millikilogram", and a milligram is a milligram, not a "microkilogram". Unless a reliable source is given for this sentence, I'm going to delete it soon. —Bkell (talk) 13:06, 9 May 2007 (UTC)

Okay, I'm going to change "kilokilogram" back to "megagram" (in effect undoing this edit). "Kilokilogram" was added by an anonymous user with no justification or sources cited. —Bkell (talk) 13:09, 9 May 2007 (UTC)
As I recall, the anonymous user was me. I must have forgotten to sign in. The kilogram is still the basic unit of mass in the SI system (see any book on physics). I'm changing it back. The confusion arises, of course, because the kilogram alone of all the basic units, has a prefix. Cheers Io 17:44, 16 May 2007 (UTC)
On second thoughts, let it stand. It is adequately explained as 1000 kilograms in the article. But a megagram is definitely not a standard word for any amount of mass. Whoever wrote the original article was probably confusing the SI with the cgs-system. As for references, let's see: Will the Handbook of Physics by Benenson, Harris, Stöcker and Lutz, Springer 2002, page 1125, translated from the 4. ed. of Taschenbuch der Physik, edited by Horst Stöcker do? Cheers Io 17:53, 16 May 2007 (UTC)
I can't say i've ever seen either megagram or kilokilogram used before but doubling up prefixes certainly seems stranger to me than the unusual prefix-unit combination of megagram. As Bkell said we don't call a gram a milikilogram or call a milligram a microkilogram. One physics textbook does not standard terminology make. Unless the SI standard has something explicit to say about this or there is evidence of widespread usage of one or both of the terms I don't think either should be mentioned in this article. Plugwash 00:05, 25 June 2007 (UTC)
Ok i've just checked the SI site and it clearly states that names for mass units should be made by applying prefixes to gram to to kilogram. Plugwash 00:34, 25 June 2007 (UTC)
Megagram(me) or Mg, see SI prefix, would be quite acceptable but so is tonne (t). The latter for convenience's sake. Peter Horn 20:14, 16 August 2007 (UTC)
Actually there could be conflict over Tonne and Metric Ton. Megagram(me) or even Mg instead.SirChan (talk) 02:22, 31 March 2008 (UTC)


Though the spelling tonne predates the introduction of the SI system in 1960, it is now used as the standard spelling for the metric mass measurement in English.

What an odd sentence. Why should the SI system have any bearing on language spelling? The sentence almost implies to me that the author was expecting the spelling of the word to be redefined by some sort of committee on weights and measures. Why not write this ....?

The spelling tonne predates the introduction of the SI system in 1960, and is now used as the standard spelling for the metric mass measurement in English.

Crysta1c1ear 17:03, 24 June 2007 (UTC)

This sentence ignores NIST's (U.S.A.) preference for "Metric Ton." It should be modified to describe it's use in non-U.S. English at least. SirChan (talk) 02:27, 31 March 2008 (UTC)

Wrong approach[edit]

I believe that the article has approached the subject backwards. It primarily describes this unit as a tonne (along with the title) while leaving the metric ton and megagram as footnotes (which redirects to tonne). It should be addressed as a megagram and then mentioning the colloquial use of the tonne and metric ton in order to be free from (allegations of) cultural bias.SirChan (talk) 21:00, 7 April 2008 (UTC)

I agree, but for a different reason. A person who has taken the trouble to learn what gram means and what mega- means should be allowed to make use of that knowledge by always referring to masses in the vicinty of the mass of an automobile with the word megagram. Forcing a person to learn yet another strange unit (tonne) places an unfair burden on readers. --Gerry Ashton (talk) 23:58, 23 April 2008 (UTC)
I agree also. If there's no other indication, should we start a megagram page with this one linked to it or should it be instead this page moved to megagram with subsections for tonnes?

--Cpt ricard (talk) 15:07, 9 September 2014 (UTC)

SI prefixes and the tonne[edit]

  • What did you do to the this article with this series of edits. Here’s what the article used to look like before you ripped out the SI prefixes. The BIPM in their CIPM, 1967: Recommendation 2 didn’t say the SI prefixes can’t be used with tonne. In fact, they didn’t say anything about the tonne. Recommendation 2 was clearly addressing the issue that you attach SI prefixes to the gram and not the kilogram. Further, SI brochure, Table 6 (Section 4.1) (“Non-SI units accepted for use with the SI, and units based on fundamental constants”) specifically includes the tonne—along with the liter—among the non-SI units that are acceptable for use with the SI. That means with the SI prefixes too. As you no doubt know (or should know), prefixed forms of the liter (one of the other non-SI units that are acceptable for use with the SI) are perfectly well accepted throughout the world (see Litre#SI prefixes applied to the litre. Are you going to go and delete the SI table from the Liter article too? In fact, the BIPM, in their French language Réglementation Métrologique (1970) (103 KB download, here) specifically acknowledges that the prefixed forms of tonne are “becoming recognized.” And that was back in 1970! You need to settle down and familiarize yourself with the world of the SI before performing such radical changes. Greg L (talk) 03:36, 24 April 2008 (UTC)

P.S. Never mind. I see you just reverted yourself. Greg L (talk) 03:38, 24 April 2008 (UTC)


In the USA this unit was defined in 1866[3] as a millier or a tonneau (both French words). This measure was used in Europe centuries earlier. - since the metric system didn't exist "centuries earlier" than 1866, what were these words used to refer to? --Random832 (contribs) 03:55, 4 July 2008 (UTC)


Googling for (Femtotonne -attotonne -"The symbol ft is shared with that for") gives no results. Therefore I've removed the reference. Rich Farmbrough, 19:25 15 July 2008 (GMT).

I vaguely remember adding that remark, probably because I noticed the symbol ft used for femtotonne in the table and found it confusing. I don't feel strongly about it, but I don't see any harm in pointing out the ambiguity to the reader. Thunderbird2 (talk) 12:57, 20 July 2008 (UTC)

Confusing sentence[edit]

This is so close to the tonne that many people draw little distinction and continue to use the old spelling.--Filll (talk | wpc) 12:48, 20 July 2008 (UTC)


Does MT refer to tonne? in here should it be interpreted like metric tonne or mega tonne? Will 11:59, 26 September 2008 (UTC) —Preceding unsigned comment added by (talk)

According to the "technical notes" link on that page (bottom left) MT means metric ton. Apparently that organization has decided to completely ignore international standards about when to use upper and lower case letters. --Gerry Ashton (talk) 15:38, 26 September 2008 (UTC)

Inconsistent redirects[edit]

Kiloton and Megaton go to TNT equivalent. Gigaton goes to Tonne. Teraton, Petaton, and Exaton all have tiny stubs. These should probably all point to the same place, but which article? --Suffusion of Yellow (talk) 01:04, 18 October 2009 (UTC)

Possibly all could redirect to Tonne, and we could have a hatnote mentioning TNT equivalent. I think tonne always refers to 1000 kg, but word usage sometimes talks about kilotons to mean TNT, without explicitly stating it. —fudoreaper (talk) 00:06, 20 October 2009 (UTC)
These units are used virtually exclusively for TNT equivalent, or not at all (exaton), so this is the more suitable redirect. I think the stubs should be redirects, maybe to Kiloton or TNT equivalent. Pol098 (talk) 13:22, 8 March 2012 (UTC)


"Ton" and "tonne" may be pronounced identically in some countries, but from where I come (Australia) we have been taught that there is a difference in pronunciation between the two words. My second edition of Macquarie Dictionary gives the phonetic spelling of "tonne" with a short "o" sound, meaning tonne rhymes with "john". The latest version of Macquarie Dictionary online also uses this pronunciation. This probably should be pointed out in the article. Wcp07 (talk) 05:35, 17 July 2011 (UTC)

If this is general usage, it could be added to the article. Pol098 (talk) 18:17, 8 March 2012 (UTC)
In UK, I've heard "tonne" pronounced as "tunny" by chemical engineers to distinguish the metric unit from the long ton. Otherwise, "tonne" is pronounced exactly the same as "ton" (i.e like "tun"). Can anyone find something WP:RS for this? Narky Blert (talk) 23:49, 4 August 2017 (UTC)

UK usage[edit]

On 8 March 2012 Google searches on two newspaper websites for
"metric tonne"
"metric tonne"
"ton" -"metric ton"
(including quotes to force exact match only) gave the following results.

Google hits Guardian Telegraph
tonne 8,610 107,000
metric ton 98 33
metric tonne 62 22
ton 16,300 59,200

"Ton" alone was more often used in a sporting context on a quick scan (100 runs in cricket, £100 bets), making it difficult to gauge how often "ton" is used as a weight. "Long ton" and "short ton" had about 10 hits in all over both papers. "Metric ton" was often used in news items from other countries, notably the US: "NASA has been watching the 6-ton (5.4-metric ton) satellite closely" and may be transcribed from international agency items and press releases.

This was a totally random search, I don't have any "position" to "support" but was trying to ascertain the facts. [Note added later: Above edited slightly for clarity about use of quotes. I should have done similar searches for the plural forms "tons", etc., but the picture is pretty clear from this and the contribution below from government sites.] Pol098 (talk) 14:39, 8 March 2012 (UTC)

I don't think that Google searches of 2 newspaper website reflects UK usage at all. For one thing, newspapers have "style guides" which dictate how they represent units of measure, which the UK population at large are not constrained by. I just did similar searches of all ".uk" domains and of just the "" domain, and got the following results:
Tonne 13,600,000 317,000
Metric ton 187,000 2,690
Metric tonne 42,300 1,770
Ton 28,400,000 435,000
-- de Facto (talk). 15:19, 8 March 2012 (UTC)
Useful additional information! One problem with newspaper sites, perhaps less so for government sites, is that the same article often appears lots of times (identical text in Google list). But the interesting conclusion is that the two searches give qualitatively very similar results: ton by itself is used a great deal, in most cases more than tonne; tonne is used a lot; metric ton is not used much (1% or less than tonne), and metric tonne even less. The use of "ton" for 100 probably skews the newspaper sites more. As appended to my original comment, I didn't think to do plurals. Pol098 (talk) 18:13, 8 March 2012 (UTC)

Missing some usages[edit]

Current text - "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, often loosely as approximate figures."

Gt and Mt are used routinely to describe units of carbon dioxide (GtCO2), e.g. in IPCC texts, country statements to UNFCCC and so on. Pg (rather than Gt) is often used to describe units of carbon (in journal papers).

So it is odd to see these units being dismissed as only used to measure energy. — Preceding unsigned comment added by Flit (talkcontribs) 21:14, 17 October 2015 (UTC)

"Short" and "Long" ton should appear in the lead section[edit]

I think that the current lead section text

  • "1.10 tons (US) or 0.984 tons (imperial)"

should be changed to something like

for the following reasons:

  • The corresponding article titles are Short ton and Long ton.
  • We should give as much context as possible, i.e. short=US, long=imperial.
  • Citing from Short ton: "In order to avoid confusion, especially in international environments, it is recommended to always use the full name: "short ton", "long ton" or "metric tonne"." According to my knowledge, Wikipedia is an international environment.
  • The text in parentheses does not appear in hovercards, so if we hide the words "short" and "long", the hovercard shows just "1.10 tons or 0.984 tons", which is confusing.

To NebY: Your reversion summary seems to assume that enwiki is just for US/UK readers - I think that it isn't. Petr Matas 16:49, 7 December 2015 (UTC)

What rhymes with tonne?[edit]

Programme Personne (not used in English spelling) Gramme Steppe (rare form of step) Matte (rare form of mat) — Preceding unsigned comment added by (talk) 03:51, 24 April 2016 (UTC)

strut, bud, dull, gun. See Help:IPA for English, and the very start of the article. --Nigelj (talk) 09:59, 24 April 2016 (UTC)
Ton. - BilCat (talk) 10:05, 24 April 2016 (UTC)
In UK - bun, dun, fun, gun, Hun, nun, pun, run, spun, stun, sun, ton, tun, won. I may have missed some. Narky Blert (talk) 23:53, 4 August 2017 (UTC)

External links modified[edit]

Hello fellow Wikipedians,

I have just modified 2 external links on Tonne. Please take a moment to review my edit. If you have any questions, or need the bot to ignore the links, or the page altogether, please visit this simple FaQ for additional information. I made the following changes:

When you have finished reviewing my changes, you may follow the instructions on the template below to fix any issues with the URLs.

You may set the |checked=, on this template, to true or failed to let other editors know you reviewed the change. If you find any errors, please use the tools below to fix them or call an editor by setting |needhelp= to your help request.

  • If you have discovered URLs which were erroneously considered dead by the bot, you can report them with this tool.
  • If you found an error with any archives or the URLs themselves, you can fix them with this tool.

If you are unable to use these tools, you may set |needhelp=<your help request> on this template to request help from an experienced user. Please include details about your problem, to help other editors.

Cheers.—InternetArchiveBot (Report bug) 15:42, 21 May 2017 (UTC)