Tonne
The tonne (/tʌn/ or /tɒn/; symbol: t) is a unit of mass equal to 1,000 kilograms. It is a non-SI unit accepted for use with SI. It is also referred to as a metric ton in the United States to distinguish it from the non-metric units of the short ton (United States customary units) and the long ton (British imperial units). It is equivalent to approximately 2,204.6 pounds, 1.102 short tons, and 0.984 long tons. The official SI unit is the megagram (Mg), a less common way to express the same amount.
This article is about the metric unit of mass. For other ton units, see Ton. For other uses of tonne, see Tonne (disambiguation). For other uses of "megagram", see Megagram (geometry).
Tonne
Megagram
mass
t
Mg
1000 kg
Symbol and abbreviations[edit]
The BIPM symbol 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 States National Institute of Standards and Technology (NIST).[2][3] It is a symbol, not an abbreviation, and should not be followed by a period. 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 the tesla, megatesla, and millitesla, respectively, while Mt and mt are SI-compatible symbols for the megatonne (one teragram) and millitonne (one kilogram). If describing TNT equivalent units of energy, one megatonne of TNT is equivalent to approximately 4.184 petajoules.
Origin and spelling[edit]
In English, tonne is an established spelling alternative to metric 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 ton is the name for this unit used and recommended by NIST;[2] an unqualified mention of a ton almost invariably refers to a short ton of 2,000 lb (907.2 kg) and to a lesser extent to a long ton of 2,240 lb (1,016 kg), with the term tonne rarely used in speech or writing. Both terms are acceptable in Canadian English.
Ton and tonne are both derived from a Germanic word in general use in the North Sea area since the Middle Ages (cf. Old English and Old Frisian tunne, Old High German and Medieval Latin tunna, German and French tonne) to designate a large cask, or tun.[8] A full tun, standing about a metre high, could easily weigh a tonne. See also the common German word de:Mülltonne (literal translation: garbage drum).
The spelling tonne pre-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 106 and above, and is now used as the standard spelling for the metric mass measurement in most English-speaking countries.[10][11][12][13] In the United States, the unit was originally referred to using the French words millier or tonneau,[14] but these terms are now obsolete.[15] The British imperial and United States customary units are comparable to the tonne and the spelling of ton in English is the same, though they differ in mass.
One tonne is equivalent to:
A tonne is the mass of one cubic metre of pure water at 4 °C (39 °F).[a]
Alternative usages[edit]
Metric ton units[edit]
A metric 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: