See also tun.

Tons that are units of mass.

Tons that are units of capacity. Most of these arise from the way carriers bill for the transport of goods.

Tons that measure neither mass nor capacity

ton (of mass)

In Great Britain and Pakistan, 2,240 pounds (1016.047 kg). It is equal to 20 hundredweights, each of 112 pounds.

In the United States, “ton” usually refers to 2000 pounds, and the 2240-pound ton is called a “long ton.” The long ton is prinicipally used for anthracite coal.

In Japan,

The ton, which is nominally of 1680 kin, and sometimes of 1700 kin. If made equal to the British ton of 2240 lbs. its value must approximate 1693.44 kin. In the Japanese coal trade, 10,000 kin are considered to be the equivalent of 6 tons

1. E. J. Blockhuys.
Vade-Mecum of Modern Metrical Units. 17ᵗʰ edition, revised and enlarged.
Tokyo: Dobunkwan, 1924.

Page 48.

assay ton

In the United States, a unit of mass, approximately 29.1667 grams. The number of milligrams of precious metal in 1 assay ton of the ore being tested is equal to the number of troy ounces of pure precious metal in one 2000-pound av. ton of the ore.


Name of unit Accepted abbreviation
Assay ton (29.1667 g) AT¹

1. In descriptive material the abbreviation for “assay ton” should be written A. T.

U. S. Dept of Commerce.
National Bureau of Standards.
Precision Laboratory Standards of Mass annd Laboratory Weights.
NBS Circular 547, sec. 1.
Washington: U.S.G.P.0., 1954.
Appendix 2. Units and Abbreviations for Marking Weights. Page 24.

deadweight ton

A measure of the carrying capacity of a ship, the number of long tons (of 2240 pounds av) it can float. Abbr, dwt.

harbour ton

In South Africa, 20ᵗʰ century, 2,000 pounds.

long ton

Convert between long tons and other major units of mass.

In the United States, 2,240 pounds (1016.047 kg). Sometimes called a gross ton. The short ton (2,000 pounds) has always been the usual ton in the United States. The long ton was principally used for anthracite coal (in Pennsylvania), for certain iron and steel products in bulk, and in estimating customs duties.

Coal Miners’ Pocketbook, 13th ed. pages 5-6.

short ton

Convert between short tons and other major units of mass.

In the United States, 2,000 pounds. Sometimes called a net ton.

metric ton or tonne

Convert between metric tons and other major units of mass.

1000 kilograms. Abbreviation, mt. By the original concept for defining masses in the metric system, a metric ton would be the mass of a cubic meter of water.

ton (of capacity)

In England, 14ᵗʰ – 18ᵗʰ centuries, a unit of capacity for wine, = 252 gallons. See tun. For a law of 1483 defining the ton at this capacity, see 1 Richard III, chapter 13.

register ton


A unit used in describing the cargo capacity of a ship, = 100 cubic feet (approximately 2.83 cubic meters). Called a tonneau de mer in Belgium. In France, the tonneau de mer is 1.44 cubic meters (about 1.88 cubic yards).

U.S. Revised Statutes, 4153 (a1909).


The volume occupied by a long ton of seawater, about 35 cubic feet.

Panama Canal net ton

A unit of capacity used in billing ships for their passage through the Panama Canal, = 100 cubic feet. In the early 1990's, for a laden ship the fee was $2.21 per Panama Canal net ton.¹

1. Frederic Allen.
Inside the Panama Canal.
American Heritage of Invention and Technology
, volume 12, number 2 (Fall 1996).

Page 22.

shipping ton


The British shipping ton, a unit of capacity, = 42 cubic feet.


The United States shipping ton = 40 cubic feet, another name for the freight ton.

freight ton

In the United States, 40 cubic feet. A common practice is to bill for shipping by volume unless a freight ton of the product shipped weighs more than 1 short ton, in which case the shipping charge is based on weight. Also called a measurement ton or United States shipping ton.

water ton

In the United Kingdom, 224 imperial gallons.

ton (of refrigeration)

Units used in refrigeration and air conditioning.

Convert between the commercial ton of refrigeration and other major units of power.

In the United States, one commercial ton of refrigeration is a rate of extraction of 200 BtuIST per minute (3516.857 joules per second), or in other terms, the rate that will freeze one short ton of ice of specific latent heat 144 BtuIT per pound in 24 hours from water at the same temperature. Symbol CTR, or CTR(US).

The U.S. standard ton of refrigeration describes an amount of cooling, not a rate. One standard ton = 288,000 Btuist removed, which is approximately the cooling provided by melting 2009.1 pounds of ice. Extracting heat at the rate of 1 commercial ton of refrigeration results in a standard ton removed each day.

The British commercial ton of refrigeration resembles the American except that it is based on a long ton (2240 pounds) of ice. About 3922.696721 joules per second. Symbol, CTR(UK). 1 CTR(UK) = 1.1154 CTR(US).

ton (of TNT)

Convert between tons of TNT and other major units of energy.

A unit of energy used to describe the size of an explosion, usually of weapons. It is equal to the energy released by the explosion of 1 short ton of TNT (trinitrotoluene), by definition 4.184 × 10⁹ joules. Usually expressed as kilotons, abbr KT, (1 kiloton = 4.184 terajoules) or megatons, abbr MT (1 megaton = 4.184 petajoules).

A 1-megaton air-burst bomb blast destroys wood frame buildings five to seven miles from the blast site. The extent of the damage is proportional to the cube root of the energy released; a 27-megaton bomb would destroy such buildings fifteen to twenty-one miles away.

Event or bomb Energy released Source
Meteor strikes
Mare Nubium on the Moon,
 11 September 2013.
15.6 ± 2.5

Josè M. Madiedo, Josè L. Ortiz, Nicolás Morales and Jesús Cabrera-Caño.
A large lunar impact blast on 2013 September 11.
Monthly Notices of the Royal Astronomical Society, vol. 439, pages 2364–2369 (2014).

Had the same object struck Earth, as much as 32 tons would have been released.

Little Boy,
fission bomb dropped
on Hiroshima, 1945.
13 kilotons  
B-61, modern American
nuclear bomb.
100 - 500 kilotons

Nuclear Weapons Databook.
Cambridge, MA: Ballinger Publishing Co.

Fireball (superbolide)
that exploded over
Chelyabinsk, Russia,
on 15 February 2013.
440 kilotons

Don Yeomans and Paul Chodas.
"Additional Details on the Large Fireball Event over Russia on Feb. 15, 2013."

Tsar Bomba,
fusion bomb tested
by U.S.S.R. in 1961.
50-58 megatons  
La Garita Caldera, Colorado. 240 gigatons

Ben G. Mason, David M. Pyle and Clive Oppenheimer.
The size and frequency of the largest explosive eruptions on Earth.
Bulletin of Volcanology, vol 66, pages 735–748 (2004)
doi 10.1007/s00445-004-0355-9

Impact of asteroid
that created Chicxulub crater,
100 teratons

Curt Covey, Stanley L. Thompson, Paul R. Weissman and Michael C. MacCracken.
Global climatic effects of atmospheric dust from an asteroid or comet impact on Earth.
Global and Planetary Change, vol 9, issues 3-4, pages 263-273 (December 1994).


a. In order to provide a yardstick for rating the total energy release of a nuclear detonation, it has become the practice to express the total yield of a nuclear device in terms of a TNT energy equivalent. For example, if the total energy of the blast, thermal radiation, and nuclear radiation released by a nuclear weapon is the same as the energy released by the detonation of 1,000 tons of TNT, the nuclear weapon is rated as a 1,000-ton, or 1-kiloton, weapon. When 1 kilogram of U-235 or plutonium undergoes fission nearly one gram (1/450 pound) of matter is converted into energy. This energy expressed in terms of TNT energy equivalence would be the same as for the detonation of 20,000 tons of TNT. Similarly, the fusion of 1 kilogram of deuterium results in the transformation of 2.65 grams of matter into energy, with an energy release equivalent to that resulting from the detonation of 57,000 tons of TNT.

b. Another method of rating in common usage, and one which is often confused with the rating of energy in terms of TNT energy equivalence, is the rating of effects in terms of TNT effects equivalence, i. e., the effect of a particular phenomenon of a nuclear detonation expressed in terms of the amount of TNT which would produce the same effect. An example of TNT effect equivalence would be the expression of the crater radius of a nuclear surface burst in terms of the amount of TNT which would be required to produce the same radius.

c. For convenience these TNT equivalences are expressed in 1,000 ton or 1,000,000 ton units, KT (kiloton) or MT (megaton), where 1 ton equals 2,000 pounds and the energy content of TNT is defined as 1100 calories per gram.

Armed Forces Special Weapons Project.
Capabilities of Atomic Weapons.
Departments of the Army, the Navy and the Air Force.
Revised edition, November 1957.
Incorporating changes of 24 June 1960.
Pages 1.1a, 1.2b.

tonnes of oil equivalent

A unit describing the energy content of a quantity of a fuel, by comparing it to the energy content of a metric tonne of oil. It is used in comparing fuel energy inputs and outputs in economies. Abbr, toe. The SI prefixes are used with this unit.

The International Energy Agency uses the following equivalents:

1 metric tonne of this product Energy equivalent
coal varies by nation
ethane 1.18 toe
liquified petroleum gases (LPG) 1.13 toe
aviation fuel 1.07 toe
automobile gasoline 1.07 toe
jet fuel 1.065 toe
kerosene 1.045 toe
middle distillates 1.035 toe
heavy fuel oil 0.96 toe
naphtha 1.075 toe
other products 0.96 toe
1 terajoule natural gas 0.00002388 Mtoe
1 terawatt-hour of electricity 0.086 Mtoe

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