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TNT equivalent is a method of quantifying the energy released in explosions. The "ton of TNT" is a unit of energy equal to 4.184 gigajoules (1 gigacalorie), which is approximately the amount of energy released in the detonation of a ton of TNT. The "megaton of TNT" is a unit of energy equal to 4.184 petajoules.
The kiloton and megaton of TNT have traditionally been used to rate the energy output, and hence destructive power, of nuclear weapons (see nuclear weapon yield) and other high-energy events. This unit is written into various nuclear weapon control treaties, and gives a sense of destructiveness as compared with ordinary explosives, like TNT. More recently, it has been used to describe the energy released in other highly destructive events, such as asteroid impacts. However, TNT is not the most energetic of conventional explosives. Dynamite, for example, has about 60% more energy density (approximately 7.5 MJ/kg, compared to about 4.7 MJ/kg for TNT).
This use of the unit named "ton" (along with the usual metric prefixes) is now one of energy, and any relationship with some mass of some explosive is relevant only in a historical sense. The use of "kilotonne" is therefore nonsensical, as this use of the term "ton" has been disconnected from its use as a unit of weight.
Historical derivation of the value
A gram of TNT releases 2673–6702 joules upon explosion. To define the ton of TNT, this was arbitrarily standardized by letting 1 gram TNT = 4184 J (exactly). This conveniently defined the energy liberated by one gram of TNT as exactly one kilocalorie.
This definition is a conventional one. The explosive's energy is normally calculated using the thermodynamic work energy of detonation, which for TNT has been accurately measured at 4686 J/g from large numbers of air blast experiments and theoretically calculated to be 4853 J/g.
A kiloton of TNT can be visualized as a cube of TNT 8.46 metres (27.8 ft) on a side.
|Grams TNT||Symbol||Tons TNT||Symbol||Energy||Corresponding mass loss|
|gram of TNT||g||microton of TNT||μt||4.184×103 J or 4.184 kilojoules||46.55 pg|
|kilogram of TNT||kg||milliton of TNT||mt||4.184×106 J or 4.184 megajoules||46.55 ng|
|megagram of TNT||Mg||ton of TNT||t||4.184×109 J or 4.184 gigajoules||46.55 μg|
|gigagram of TNT||Gg||kiloton of TNT||kt||4.184×1012 J or 4.184 terajoules||46.55 mg|
|teragram of TNT||Tg||megaton of TNT||Mt||4.184×1015 J or 4.184 petajoules||46.55 g|
|petagram of TNT||Pg||gigaton of TNT||Gt||4.184×1018 J or 4.184 exajoules||46.55 kg|
Conversion to other units
1 ton TNT equivalent is approximately:
- 1.0×109 calories
- 4.184×109 joules
- 3.96831×106 British thermal units
- 3.08802×109 foot pounds
- 1.162×103 kilowatt hours
|Megatons of TNT||Description|
|0.00000001||The approximate radiant heat energy released during 3-phase 600 V 100 kA arcing fault in a 0.5 × 0.5 × 0.5 m (20 × 20 × 20 in) compartment within a 1-second time interval.[further explanation needed]|
|0.000001–0.000044||Conventional bombs yield range from less than 1 ton to FOAB's 44 tonnes.|
|0.0000025||The MythBusters homemade diamonds episode used 2.5 tons of ANFO to make diamonds.|
|0.0005||A real 0.5-kilotonne-of-TNT (2.1 TJ) charge at Operation Sailor Hat. If the charge were a full sphere, it would be 1 kilotonne of TNT (4.2 TJ).|
|0.001-0.002||Estimated yield of the Oppau explosion in 1921 at a German fertilizer factory, killing more than 500.|
|0.0023||Amount of solar energy falling on 4,000 m2 (1 acre) of land in a year is 9.5 TJ (2,650 MWh) (an average over the Earth's disk).|
|0.003||The Halifax Explosion in 1917 involved the accidental detonation of 3,000 tons of TNT.|
|0.008||Minor Scale, a 1985 United States conventional explosion utilizing 4,744 tons of ANFO explosive to provide a scaled equivalent airblast of an 8 kiloton (33.44 TJ) nuclear device, is believed to be the largest planned detonation of conventional explosives in history.|
|0.015–0.02||The Little Boy atomic bomb dropped on Hiroshima on August 6, 1945 exploded with an energy of about 15 kilotons of TNT (63 TJ), and the Fat Man atomic bomb dropped on Nagasaki on August 9, 1945 exploded with an energy of about 20 kilotons of TNT (84 TJ). The nuclear weapons currently in the arsenal of the United States range in yield from 0.3 kt (1.3 TJ) to 1.2 Mt (5.0 PJ) equivalent, for the B83 strategic bomb.|
|1||The energy contained in 1 megaton of TNT (4.2 PJ) is enough to power the average American household (in the year 2007) for 103,474 years. For example, the 30 Mt (130 PJ) estimated upper limit blast power of the Tunguska event could power the aforementioned home for just over 3,104,226 years. To put that in perspective: the blast energy could power the entire United States for 3.27 days.|
|3||The total energy of all explosives used in World War Two (including the Hiroshima and Nagasaki bombs) is estimated to have been 3 megatons of TNT.|
|8.6||The amount of energy released by a "average" tropical cyclone in 1 minute, mainly due to water condensation. Winds are a quarter of a percent of that amount.|
|21.5||The maximum theoretical yield from 1 kg of matter by converting all of the mass into energy (by mass–energy equivalence, E = mc2) yields 89.8 petajoules or the equivalent of 21.5 megatons of TNT. No practical method of total conversion exists today, such as combining 500 grams of matter with 500 grams of antimatter. However, in the case of proton–antiproton annihilation, approximately 50% of the released energy will escape in the form of neutrinos, which are almost undetectable. Electron–positron annihilation events emit their energy entirely as gamma rays.|
|25, 50, 100||During the Cold War, the United States developed hydrogen bombs with a maximum theoretical yield of 25 megatons of TNT (100 PJ); the Soviet Union developed a prototype weapon, nicknamed the Tsar Bomba, which was tested at 50 Mt (210 PJ), but had a maximum theoretical yield of 100 Mt (420 PJ). The actual destructive potential of such weapons can vary greatly depending on conditions, such as the altitude at which they are detonated, the nature of the target they are detonated against, and the physical features of the landscape where they are detonated.|
|26.3||Megathrust earthquakes 2004 Indian Ocean Earthquake released record ME surface rupture energy, or potential for damage at 26.3 megatons of TNT (110 PJ). See total energy released 6 steps below.|
|540||The total amount of all nuclear testing and combat from 1945 to present is about 540 megatons.|
|7,000||The total global nuclear arsenal is about 30,000 nuclear warheads with a destructive capacity of 7,000 megatons or 7 gigatons (7,000 million tons) of TNT.|
|62,500||The amount of total solar energy input to the Earth per minute is 440 exajoules.|
|6,000,000 = 6×106||The approximate energy released when the largest fragment of Comet Shoemaker–Levy 9 impacted Jupiter was estimated to be equal to 6 million megatons (or 6 trillion tons) of TNT.|
|9.32×106||The amount of energy released in the 2011 Tōhoku earthquake and tsunami was over 200,000 times the surface energy and was calculated by the USGS at 3.9×1022 joules, slightly less than the 2004 Indian Ocean quake. This is equivalent to 9,320 gigatons of TNT, or approximately 600 million times the energy of the Hiroshima bomb.|
|9.56×106||Megathrust earthquakes record huge MW values, or total energy released. The 2004 Indian Ocean Earthquake released 9,560 gigatons TNT equivalent.|
|1×108||The approximate energy released when the Chicxulub impact caused the mass extinction 66 million years ago was estimated to be equal to 100 teratons (i.e. 100 exagrams or approximately 220.462 quadrillion pounds) of TNT. That is roughly 8 billion times stronger than each of the bombs that hit Hiroshima and Nagasaki and the most energetic event on the history of Earth for hundreds of millions of years, far more powerful than any volcanic eruption, earthquake or firestorm. Such an explosion annihilated everything within a thousand miles of the impact in a split second. Such energy is equivalent to that needed to power the whole Earth for several centuries.|
|7.89×1015||Total solar output in all directions per day.|
|2×1028||On a much grander scale, a type 1a supernova explosion gives off 1–2x1044 joules of energy, which is about a hundred billion yottatons (ten octillion (1028) megatons) of TNT, equivalent to the explosive force of a quantity of TNT a trillion (1012) times the mass of the planet Earth. The Type 1a supernova is essentially the fusion detonation of all the fusable fuel in a star of about 1.4 solar masses within a few seconds, and is a standard candle used for intergalactic distance measurements.|
|2×1030||The largest supernova explosions witnessed, so-called Gamma-ray bursts (GRBs) released more than 1046 joules of energy.|
For more, see Orders of magnitude (energy).
- Nuclear arms race
- Orders of magnitude (energy)
- Relative effectiveness factor
- Tonne of oil equivalent, a unit of energy almost exactly 10 tonnes of TNT
- Table of explosive detonation velocities
- Joules to Megatons Conversion Calculator
- Blast effects of external explosions (Section 4.8. Limitations of the TNT equivalent method)
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