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"Kiloton" and "Megaton" redirect here. For the
similarly-named weight measurements, see Tonne
Diagram of explosive yield vs mushroom cloud height, illustrating
the difference between 22 kiloton Fat Man
and 15 megaton Castle Bravo
TNT equivalent is a method of quantifying the
energy released in explosions. The ton (or
tonne) of TNT is a unit of energy
equal to 4.184 gigajoules, which
is approximately the amount of energy released in the detonation of
one ton of TNT. The megaton is a
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). 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 more than 60% more
energy density (approximately 7.5 MJ/kg, compared to 4.6 MJ/kg for
A gram of TNT releases 980–1100 calories upon explosion. To
define the tonne of TNT, this was arbitrarily
standardized by letting 1000 thermochemical calories = 1 gram TNT =
4184 J (exactly).
This definition is a conventional one. Explosives' energy is
normally calculated using the thermodynamic
work energy of detonation, which for TNT has been accurately
measured at 1120 calth/g from large numbers of air
blast experiments and theoretically calculated to be
The measured pure heat output
of a gram of TNT is only 651 thermochemical
calories ≈ 2724 J, but
this is not the important value for explosive blast effect
A kiloton of TNT can be visualized as a cube of TNT a bit under
10 meters on a side.
|gram of TNT
||microton of TNT
||4.184 × 103 J
|kilogram of TNT
||milliton of TNT
||4.184 × 106 J
|megagram of TNT
||ton of TNT
||4.184 × 109 J
|gigagram of TNT
||kiloton of TNT
||4.184 × 1012 J
|teragram of TNT
||megaton of TNT
||4.184 × 1015 J
|petagram of TNT
||gigaton of TNT
||4.184 × 1018 J
- Conventional bunker buster bombs yield range from less
than 1 ton to MOAB's 11 tonnes.
- Minor Scale, a 1985 United States
conventional explosion utilizing 4,800 short tons
(4,400 t) of ANFO explosive
to simulate a 4 kilotons of TNT (17 TJ) nuclear
explosion, is believed to be the largest planned detonation of
conventional explosives in history.
- The Little Boy atomic
bomb dropped on Hiroshima on August 6, 1945, exploded with an
energy of about 15 kilotons of TNT (63 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.
- 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, nick-named 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
- 1 megaton of TNT (4.2 PJ), when converted to
kilowatt-hours, produces enough energy 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.
- Megathrust earthquakes record
huge MW values, or total energy released. The
Indian Ocean Earthquake released 9,560 gigatons of TNT
(40,000 EJ) equivalent, but its ME
(surface rupture energy, or potential for damage) was far smaller
at 26.3 megatons of TNT (110 PJ).
- On a much grander scale, supernova explosions give off about
1044 joules of energy, which is about ten octillion
(1028) megatons of TNT.
- The maximum theoretical energy from total conversion of matter to
energy when 1 kilogram (2.2 lb) of antimatter annihilates with 1
kilogram of matter the reaction is
17.975 × 1016 J, which is equal to
42.92 Mt. This is given by the equation E = mc2.
Joules to Megatons Conversion
NIST Guide for the Use of the
International System of Units (SI): Appendix B8—Factors for Units
Cooper, Paul. Explosives Engineering, New York: Wiley-VCH,
1996, p. 406.
"Physics for Future
Presidents, a textbook", 2001–2002, Richard A. Muller, Chapter 1.
Energy, Power, and Explosions
See Currently deployed U.S.
nuclear weapon yields, Complete List of All U.S.
Nuclear Weapons, Tsar Bomba, all from Carey
Sublette's Nuclear Weapon Archive.
"Frequently Asked Questions –
Electricity". United States Department
of Energy. 2009-10-06. http://tonto.eia.doe.gov/ask/electricity_faqs.asp#electricity_use_home. Retrieved
2007 value of 936 kWh monthly usage)
"Country Comparison ::
Electricity - consumption". The World Factbook. CIA. https://www.cia.gov/library/publications/the-world-factbook/rankorder/2042rank.html. Retrieved
2007 value of 3,892,000,000,000 kWh annual usage)
In antiproton annihilation, about
50% of this energy is carried off by effectively invisible neutrinos (see S.K. Borowski,Comparison of
Fusion/Antiproton Propulsion systems); in contrast, almost 100%
of electron-positron annihilation events emit
their energy entirely as gamma rays.