Ton is the name of any one of several
units of measure
A unit of measurement is a definite magnitude of a quantity, defined and adopted by convention or by law, that is used as a standard for measurement of the same kind of quantity. Any other quantity of that kind can be expressed as a multi ...
. It has a long history and has acquired several meanings and uses.
Mainly it describes units of weight. Confusion can arise because ''ton'' can mean
* the
long ton, which is 2,240
pounds
* the
short ton
The short ton (symbol tn) is a measurement unit equal to . It is commonly used in the United States, where it is known simply as a ton,
although the term is ambiguous, the single word being variously used for short, long, and metric ton.
The vari ...
, which is 2,000 pounds
* the
tonne
The tonne ( or ; symbol: t) is a unit of mass equal to 1000 kilograms. It is a non-SI unit accepted for use with SI. It is also referred to as a metric ton to distinguish it from the non-metric units of the short ton ( United State ...
, also called the ''metric ton'', which is 1,000
kilogram
The kilogram (also kilogramme) is the unit of mass in the International System of Units (SI), having the unit symbol kg. It is a widely used measure in science, engineering and commerce worldwide, and is often simply called a kilo colloquially ...
s or 1
megagram.
Its original use as a measurement of
volume
Volume is a measure of occupied three-dimensional space. It is often quantified numerically using SI derived units (such as the cubic metre and litre) or by various imperial or US customary units (such as the gallon, quart, cubic inch). The de ...
has continued in the capacity of cargo ships and in terms such as the ''freight ton'' and a number of other units, ranging from in capacity. Recent specialized uses include the ton as a measure of energy and as a means of
truck classification
Truck classifications are typically based upon the maximum loaded weight of the truck, typically using the gross vehicle weight rating (GVWR) and sometimes also the gross trailer weight rating (GTWR), and can vary among jurisdictions.
United ...
. It can also be used as a unit of
energy
In physics, energy (from Ancient Greek: ἐνέργεια, ''enérgeia'', “activity”) is the quantitative property that is transferred to a body or to a physical system, recognizable in the performance of work and in the form of heat a ...
, or in refrigeration as a unit of
power
Power most often refers to:
* Power (physics), meaning "rate of doing work"
** Engine power, the power put out by an engine
** Electric power
* Power (social and political), the ability to influence people or events
** Abusive power
Power may a ...
, sometimes called a ''
ton of refrigeration
A ton of refrigeration (TR or TOR), also called a refrigeration ton (RT), is a unit of power used in some countries (especially in North America) to describe the heat-extraction capacity of refrigeration and air conditioning equipment.
It was orig ...
''.
Because the ton (of any system of measuring weight) is usually the heaviest unit named in
colloquial
Colloquialism (), also called colloquial language, everyday language or general parlance, is the linguistic style used for casual (informal) communication. It is the most common functional style of speech, the idiom normally employed in conver ...
speech, its name also has figurative uses, singular and plural, informally meaning a large amount or quantity, or to a great degree, as in "There's a ton of bees in this hive", "We have tons of homework", and "I love you a ton."
History
The ton is derived from the ''
tun
TUN or tun may refer to:
Biology
* Tun shells, large sea snails of the family ''Tonnidae''
* Tun, a tardigrade in its cryptobiotic state
* Tun or Toon, common name for trees of the genus '' Toona''
Places
* Tun, Sweden, a locality in Västra G ...
'', the term applied to a cask of the largest capacity. This could contain a volume between , which could weigh around and occupy some of space.
[. "Historically, a very important and standard cargo for European sailing vessels was wine, stored and shipped in casks called tuns. These tuns of wine, because of their uniform size and their universal demand, became a standard by which a ship's capacity could be measured. A tun of wine weighed approximately 2,240 pounds, and occupied nearly 60 cubic feet." ( Gillmer, Thomas (1975). ''Modern Ship Design''. United States Naval Institute.) "Today the ship designers standard of weight is the long ton which is equal to 2,240 pounds." This is the weight of 35 cubic feet of Sea Water at a specific gravity of 1.025, compared to Fresh Water, specific gravity of 1.000 usually measured at 60 degrees F. Handy numbers: 35, 36, 37, number of Cubic Feet per Salt Water, Fresh Water and Lube Oil.]
Units of mass/weight
There are several similar units of
mass
Mass is an intrinsic property of a body. It was traditionally believed to be related to the quantity of matter in a physical body, until the discovery of the atom and particle physics. It was found that different atoms and different elementar ...
or volume called the ton.
Where precision is required the correct term should be used, as the difference between the short ton and the other common forms ("long" and "metric") is about 10%. However, when comparing between the metric and long tons, precision may not be as necessary as they differ by only 1.6%.
The metric tonne is usually distinguished by its spelling when written, but in the US and UK it is pronounced the same as ton, hence is often spoken as "metric ton" when it is necessary to make the distinction. In the UK the final "e" of "tonne" can also be pronounced (),
. In Australia, it is pronounced .
In the United Kingdom, the (
Imperial
Imperial is that which relates to an empire, emperor, or imperialism.
Imperial or The Imperial may also refer to:
Places
United States
* Imperial, California
* Imperial, Missouri
* Imperial, Nebraska
* Imperial, Pennsylvania
* Imperial, Texa ...
) ton is a
statute measure
Weights and measures acts are acts of the British Parliament determining the regulation of weights and measures. It also refers to similar royal and parliamentary acts of the Kingdoms of England and Scotland and the medieval Welsh states. T ...
, defined as 2,240
pounds (about ).
In the United States and Canada,
a ton is defined to be .
Other units of mass/weight
*
Deadweight ton
Deadweight tonnage (also known as deadweight; abbreviated to DWT, D.W.T., d.w.t., or dwt) or tons deadweight (DWT) is a measure of how much weight a ship can carry. It is the sum of the weights of cargo, fuel, fresh water, Sailing ballast#Water ...
(abbreviation 'DWT' or 'dwt') is a measure of a ship's carrying capacity, including bunker oil, fresh water, ballast water, crew and provisions. It is expressed in tonnes (1,000 kg) or long tons (). This measurement is also used in the U.S. tonnage of naval ships.
* Increasingly,
tonne
The tonne ( or ; symbol: t) is a unit of mass equal to 1000 kilograms. It is a non-SI unit accepted for use with SI. It is also referred to as a metric ton to distinguish it from the non-metric units of the short ton ( United State ...
s are being used rather than long tons in measuring the
displacement of ships.
*Harbour ton, used in South Africa in the 20th century, was equivalent to 2,000 pounds or one short ton.
Assay ton (abbreviation 'AT') is not a unit of measurement but a standard quantity used in
assay
An assay is an investigative (analytic) procedure in laboratory medicine, mining, pharmacology, environmental biology and molecular biology for qualitatively assessing or quantitatively measuring the presence, amount, or functional activity of a ...
ing ores of precious metals. A short assay ton is grams while a long assay ton is gram. These amounts bear the same ratio to a milligram as a short or long ton bears to a
troy ounce
Troy weight is a system of units of mass that originated in 15th-century England, and is primarily used in the precious metals industry. The troy weight units are the grain, the pennyweight (24 grains), the troy ounce (20 pennyweights), and the ...
. Therefore, the number of milligrams of a particular metal found in a sample weighing one assay ton gives the number of troy ounces of metal contained in a ton of ore.
In documents that predate 1960 the word ''ton'' is sometimes spelled ''tonne'', but in more recent documents ''tonne'' refers exclusively to the
metric ton
The tonne ( or ; symbol: t) is a unit of mass equal to 1000 kilograms. It is a non-SI unit accepted for use with SI. It is also referred to as a metric ton to distinguish it from the non-metric units of the short ton (United States c ...
.
In
nuclear power plant
A nuclear power plant (NPP) is a thermal power station in which the heat source is a nuclear reactor. As is typical of thermal power stations, heat is used to generate steam that drives a steam turbine connected to a electric generator, generato ...
s tHM and MTHM mean tonnes of
heavy metals
upright=1.2, Crystals of osmium, a heavy metal nearly twice as dense as lead">lead.html" ;"title="osmium, a heavy metal nearly twice as dense as lead">osmium, a heavy metal nearly twice as dense as lead
Heavy metals are generally defined as ...
, and MTU means tonnes of
uranium
Uranium is a chemical element with the symbol U and atomic number 92. It is a silvery-grey metal in the actinide series of the periodic table. A uranium atom has 92 protons and 92 electrons, of which 6 are valence electrons. Uranium is weak ...
. In the
steel
Steel is an alloy made up of iron with added carbon to improve its strength and fracture resistance compared to other forms of iron. Many other elements may be present or added. Stainless steels that are corrosion- and oxidation-resistant ty ...
industry, the abbreviation THM means 'tons/tonnes hot metal', which refers to the amount of liquid iron or steel that is produced, particularly in the context of
blast furnace
A blast furnace is a type of metallurgical furnace used for smelting to produce industrial metals, generally pig iron, but also others such as lead or copper. ''Blast'' refers to the combustion air being "forced" or supplied above atmospheric ...
production or specific consumption.
A dry ton or dry tonne has the same mass value, but the material (
sludge
Sludge is a semi-solid slurry that can be produced from a range of industrial processes, from water treatment, wastewater treatment or on-site sanitation systems. For example, it can be produced as a settled suspension obtained from conventiona ...
, slurries,
compost
Compost is a mixture of ingredients used as plant fertilizer and to improve soil's physical, chemical and biological properties. It is commonly prepared by decomposing plant, food waste, recycling organic materials and manure. The resulting m ...
, and similar mixtures in which solid material is soaked with or suspended in
water
Water (chemical formula ) is an inorganic, transparent, tasteless, odorless, and nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living organisms (in which it acts as a ...
) has been dried to a relatively low, consistent
moisture
Moisture is the presence of a liquid, especially water, often in trace amounts. Small amounts of water may be found, for example, in the air (humidity), in foods, and in some commercial products. Moisture also refers to the amount of water vapo ...
level (
dry weight
Vehicle weight is a measurement of wheeled motor vehicles; either an actual measured weight of the vehicle under defined conditions or a gross weight rating for its weight carrying capacity.
Curb or kerb weight
Curb weight (U.S. English) or kerb ...
). If the material is in its natural, wet state, it is called a wet ton or wet tonne.
Subdivisions
Both the UK definition of long ton and US definition of short ton have the same underlying basis. Each is equivalent to 20
long
Long may refer to:
Measurement
* Long, characteristic of something of great duration
* Long, characteristic of something of great length
* Longitude (abbreviation: long.), a geographic coordinate
* Longa (music), note value in early music mens ...
or
short hundredweight, being and respectively.
Before the twentieth century there were several definitions. Prior to the 15th century in England, the ton was 20 hundredweight, each of 108 lb, giving a ton of . In the nineteenth century in different parts of Britain, definitions of 2,240, 2,352, and 2,400 lb were used, with 2,000 lb for explosives; the legal ton was usually 2,240 lb.
In the United Kingdom, Canada, Australia, and other areas that had used the imperial system, the tonne is the form of ton legal in trade.
Units of volume
The
displacement
Displacement may refer to:
Physical sciences
Mathematics and Physics
*Displacement (geometry), is the difference between the final and initial position of a point trajectory (for instance, the center of mass of a moving object). The actual path ...
, essentially the weight, of a ship is traditionally expressed in
long tons. To simplify measurement it is determined by measuring the
volume
Volume is a measure of occupied three-dimensional space. It is often quantified numerically using SI derived units (such as the cubic metre and litre) or by various imperial or US customary units (such as the gallon, quart, cubic inch). The de ...
, rather than weight, of water displaced, and calculating the weight from the volume and density.
For practical purposes the displacement ton (DT) is a unit of volume, , the approximate volume occupied by one ton of
seawater
Seawater, or salt water, is water from a sea or ocean. On average, seawater in the world's oceans has a salinity of about 3.5% (35 g/L, 35 ppt, 600 mM). This means that every kilogram (roughly one liter by volume) of seawater has appro ...
(the actual volume varies with salinity and temperature). It is slightly less than the 224 imperial gallons (1.018 m
3) of the water ton (based on
distilled water
Distilled water is water that has been boiled into vapor and condensed back into liquid in a separate container. Impurities in the original water that do not boil below or near the boiling point of water remain in the original container. Thus, di ...
).
One
measurement ton or freight ton is equal to , but historically it has had several different definitions. It is used to determine the amount of money to be charged in loading, unloading, or carrying different sorts of cargo. In general if a cargo is heavier than salt water, the actual tonnage is used. If it is lighter than salt water, e.g. feathers, freight is calculated using Measurement Tons of 40 cubic feet.
Gross tonnage
Gross tonnage (GT, G.T. or gt) is a nonlinear measure of a ship's overall internal volume. Gross tonnage is different from gross register tonnage. Neither gross tonnage nor gross register tonnage should be confused with measures of mass or weigh ...
and
net tonnage are volumetric measures of the cargo-carrying capacity of a ship.
The Panama Canal/Universal Measurement System (PC/UMS) is based on
net tonnage, modified for Panama Canal billing purposes. PC/UMS is based on a mathematical formula to calculate a vessel's total volume; a PC/UMS net ton is equivalent to 100 cubic feet of capacity.
The water ton is used chiefly in Great Britain, in statistics dealing with petroleum products, and is defined as , the volume occupied by of water under the conditions that define the
imperial
Imperial is that which relates to an empire, emperor, or imperialism.
Imperial or The Imperial may also refer to:
Places
United States
* Imperial, California
* Imperial, Missouri
* Imperial, Nebraska
* Imperial, Pennsylvania
* Imperial, Texa ...
gallon
The gallon is a unit of volume in imperial units and United States customary units. Three different versions are in current use:
*the imperial gallon (imp gal), defined as , which is or was used in the United Kingdom, Ireland, Canada, Austral ...
.
Units of energy and power
Ton of TNT
*A ton of TNT or ''tonne of TNT'' is a unit of energy equal to 10
9 (thermochemical)
calorie
The calorie is a unit of energy. For historical reasons, two main definitions of "calorie" are in wide use. The large calorie, food calorie, or kilogram calorie was originally defined as the amount of heat needed to raise the temperature of on ...
s, also known as a gigacalorie (Gcal), equal to 4.184
gigajoule
The joule ( , ; symbol: J) is the unit of energy in the International System of Units (SI). It is equal to the amount of work done when a force of 1 newton displaces a mass through a distance of 1 metre in the direction of the force applied. ...
s (GJ).
*A kiloton of TNT or ''kilotonne of TNT'' is a unit of energy equal to 10
12 calories, also known as a teracalorie (Tcal), equal to 4.184 terajoules (TJ).
*A megaton of TNT (1,000,000 tonnes) or ''megatonne of TNT'' is a unit of energy equal to 10
15 calories, also known (infrequently) as a petacalorie (Pcal), equal to 4.184 petajoules (PJ).
Note that these are small calories (cal). The large or dietary calorie (Cal) is equal to one kilocalorie (kcal), and is gradually being replaced by the latter correct term.
Early values for the explosive energy released by
trinitrotoluene
Trinitrotoluene (), more commonly known as TNT, more specifically 2,4,6-trinitrotoluene, and by its preferred IUPAC name 2-methyl-1,3,5-trinitrobenzene, is a chemical compound with the formula C6H2(NO2)3CH3. TNT is occasionally used as a reage ...
(TNT) ranged from 900 to 1100 calories per gram. In order to standardise the use of the term ''TNT'' as a unit of energy, an arbitrary value was assigned based on 1,000 calories () per gram. Thus there is no longer a direct connection to the chemical TNT itself. It is now merely a unit of energy that happens to be expressed using words normally associated with mass (e.g., kilogram, tonne, pound). The definition applies for both spellings: ''ton of TNT'' and ''tonne of TNT''.
Measurements in tons of TNT have been used primarily to express
nuclear weapon yield
The explosive yield of a nuclear weapon is the amount of energy released when that particular nuclear weapon is detonated, usually expressed as a TNT equivalent (the standardized equivalent mass of trinitrotoluene which, if detonated, would produ ...
s, though they have also been used since in
seismology
Seismology (; from Ancient Greek σεισμός (''seismós'') meaning "earthquake" and -λογία (''-logía'') meaning "study of") is the scientific study of earthquakes and the propagation of elastic waves through the Earth or through other ...
as well.
Tonne of oil equivalent
A
tonne of oil equivalent
The tonne of oil equivalent (toe) is a unit of energy defined as the amount of energy released by burning one tonne of crude oil. It is approximately 42 gigajoules or 11.630 megawatt-hours, although as different crude oils have different calorifi ...
(toe), sometimes ''ton of oil equivalent'', is a conventional value, based on the amount of energy released by burning one tonne of crude oil. The unit is used, for example, by the International Energy Agency (IEA), for the reported
world energy consumption
World energy supply and consumption is global production and preparation of fuel, generation of electricity, energy transport, and energy consumption. It is a basic part of economic activity. It includes heat, but not energy from food.
This art ...
as
TPES
Primary energy (PE) is an energy form found in nature that has not been subjected to any human engineered conversion process. It is energy contained in raw fuels, and other forms of energy, including waste, received as input to a system. Pr ...
in millions of toe (Mtoe).
[
]
Other sources convert 1 toe into 1.28
tonne of coal equivalent
The tonne ( or ; symbol: t) is a unit of mass equal to 1000 kilograms. It is a non-SI unit accepted for use with SI. It is also referred to as a metric ton to distinguish it from the non-metric units of the short ton ( United State ...
(tce). 1 toe is also standardized as 7.33
barrel of oil equivalent
The barrel of oil equivalent (BOE) is a unit of energy based on the approximate energy released by burning one barrel (, or ) of crude oil. The BOE is used by oil and gas companies in their financial statements as a way of combining oil and nat ...
(boe).
Tonne of coal equivalent
A tonne of coal equivalent (tce), sometimes ''ton of coal equivalent'', is a conventional value, based on the amount of energy released by burning one tonne of coal. Plural name is ''tonnes of coal equivalent''.
* Per the
World Coal Association
The World Coal Association (WCA) is an international non-profit, non-governmental association based in London, United Kingdom. It was created to represent the global coal industry. The association was formerly called the World Coal Institute (WCI ...
: 1 tonne of coal equivalent (tce) corresponds to 0.697
tonne of oil equivalent
The tonne of oil equivalent (toe) is a unit of energy defined as the amount of energy released by burning one tonne of crude oil. It is approximately 42 gigajoules or 11.630 megawatt-hours, although as different crude oils have different calorifi ...
(toe)
* Per the
International Energy Agency
The International Energy Agency (IEA) is a Paris-based autonomous intergovernmental organisation, established in 1974, that provides policy recommendations, analysis and data on the entire global energy sector, with a recent focus on curbing carb ...
1 tonne of coal equivalent (tce) corresponds to 0.700
tonne of oil equivalent
The tonne of oil equivalent (toe) is a unit of energy defined as the amount of energy released by burning one tonne of crude oil. It is approximately 42 gigajoules or 11.630 megawatt-hours, although as different crude oils have different calorifi ...
(toe)
Refrigeration
The unit ''ton'' is used in
refrigeration
The term refrigeration refers to the process of removing heat from an enclosed space or substance for the purpose of lowering the temperature.International Dictionary of Refrigeration, http://dictionary.iifiir.org/search.phpASHRAE Terminology, ht ...
and
air conditioning
Air conditioning, often abbreviated as A/C or AC, is the process of removing heat from an enclosed space to achieve a more comfortable interior environment (sometimes referred to as 'comfort cooling') and in some cases also strictly controlling ...
to measure the rate of heat absorption. Prior to the introduction of mechanical refrigeration, cooling was accomplished by delivering ice. Installing one
ton of mechanical refrigeration capacity replaced the daily delivery of one ton of ice.
* In North America, a standard ton of refrigeration is . "The
heat absorption per day is approximately the
heat of fusion
In thermodynamics, the enthalpy of fusion of a substance, also known as (latent) heat of fusion, is the change in its enthalpy resulting from providing energy, typically heat, to a specific quantity of the substance to change its state from a s ...
of 1 ''ton'' of ice at ." This is approximately the power required to melt one short ton () of ice at in 24 hours, thus representing the delivery of of ice per day.
* A less common usage is the power required to cool 1 long ton ( = ) of water by every 10 minutes = .
The refrigeration ton is commonly abbreviated as RT.
Informal tons
*Ton is also used informally, often as
slang
Slang is vocabulary (words, phrases, and linguistic usages) of an informal register, common in spoken conversation but avoided in formal writing. It also sometimes refers to the language generally exclusive to the members of particular in-gro ...
, to mean a large amount of something.
*In
Britain
Britain most often refers to:
* The United Kingdom, a sovereign state in Europe comprising the island of Great Britain, the north-eastern part of the island of Ireland and many smaller islands
* Great Britain, the largest island in the United King ...
, a ton is colloquially used to refer to 100 of a given unit. Ton can thus refer to a speed of 100 miles per hour, and is prefixed by an indefinite article, e.g. "Lee was doing a ton down the motorway"; to money e.g. "How much did you pay for that?" "A ton" (£100); to 100 points in a game e.g. "Eric just threw a ton in our darts game" (in some games, e.g.
cricket
Cricket is a bat-and-ball game played between two teams of eleven players on a field at the centre of which is a pitch with a wicket at each end, each comprising two bails balanced on three stumps. The batting side scores runs by striki ...
, more commonly called a century); or to a hundred of any other countable figure.
*In
Dutch
Dutch commonly refers to:
* Something of, from, or related to the Netherlands
* Dutch people ()
* Dutch language ()
Dutch may also refer to:
Places
* Dutch, West Virginia, a community in the United States
* Pennsylvania Dutch Country
People E ...
, when talking about money a ton is used to indicate
100,000. For example a house costing 2 ton would cost 200,000 euros. This convention has been in use since at least the 18th century.
[''A Description of Holland'']
page 267
J. and P. Knapton, 1743.
*In
Finnish
Finnish may refer to:
* Something or someone from, or related to Finland
* Culture of Finland
* Finnish people or Finns, the primary ethnic group in Finland
* Finnish language, the national language of the Finnish people
* Finnish cuisine
See also ...
, is often used as a synonym for 1,000, especially when referring to money. For example, was a 1000-
mark
Mark may refer to:
Currency
* Bosnia and Herzegovina convertible mark, the currency of Bosnia and Herzegovina
* East German mark, the currency of the German Democratic Republic
* Estonian mark, the currency of Estonia between 1918 and 1927
* Fi ...
banknote
A banknote—also called a bill (North American English), paper money, or simply a note—is a type of negotiable instrument, negotiable promissory note, made by a bank or other licensed authority, payable to the bearer on demand.
Banknotes w ...
, and a popular TV show was called ("ten tons" = 10,000 marks).
See also
*
Conversion of units
Conversion of units is the conversion between different units of measurement for the same quantity, typically through multiplicative conversion factors which change the measured quantity value without changing its effects.
Overview
The process ...
*
Systems of measurement
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 i ...
*
English units
English units are the units of measurement used in England up to 1826 (when they were replaced by Imperial units), which evolved as a combination of the Anglo-Saxon and Roman systems of units. Various standards have applied to English units at ...
*
Imperial units
The imperial system of units, imperial system or imperial units (also known as British Imperial or Exchequer Standards of 1826) is the system of units first defined in the British Weights and Measures Act 1824 and continued to be developed thro ...
*
United States customary units
United States customary units form a system of measurement units commonly used in the United States and U.S. territories since being standardized and adopted in 1832. The United States customary system (USCS or USC) developed from English units ...
*
Gross ton mile
References
{{United States Customary Units
Units of mass
Units of volume
Customary units of measurement in the United States
Imperial units
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no:Megagram
nn:Megagram
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