Energy in a Ton of TNT
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| Bibliographic Entry | Result (w/surrounding text) |
Standardized Result |
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|---|---|---|---|---|---|---|
| Herter, Terry. Lecture 3: Cosmic Forces. | "Some everyday and not so everyday examples of energies… 4 × 109 J = 1 ton of TNT" | 4 × 109 J | ||||
| "Explosives." Encyclopedia Americana. 2nd Ed. Connecticut: Grolier, 2001 |
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4.25 × 109 J | ||||
| Revelle, D. O. Global Infrasonic Monitoring of Large Meteoroids. | "We now know empirically how to relate the period at maximum amplitude of the sound waves to the source of energy. For the blast radius values quoted above sources energies range from -0.00001 kt (1/100 of a ton of TNT to 10 Mt of TNT equivalent (kt = 4.186 × 109 J" | 4.186 × 109 J | ||||
| Newburn, Ray L. Appendix A: Comparative Tables. | "Two 3,500 lb. cars colliding head-on at 55 mph - 9.6 × 105 J to 1…. Explosion of 1 US ton of TNT - 4.2 × 105 J to 4,271." | 4.2 × 109 J |
TNT2, 4,6-Trinitrotoluene, commonly known as TNT, is a yellow, odorless solid that does not occur naturally in the environment. As research in the field of explosives developed there came to be different forms and designs of TNT. So in turn did the energy content change. After the development of atomic weapons there needed to be a standard way of counting the power in a bomb so there was a set value set. This value came to be 4.186 × 109 J. There are of course many variances on this as this research proves but the energy came to be around 4.2 × 109 J.
Alex Roslyakov -- 2002
| Bibliographic Entry | Result (w/surrounding text) |
Standardized Result |
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|---|---|---|---|---|---|---|
| Robertson, Robert. Some War Developments of Explosives. Nature. Vol. 107 (1921): 524–527. |
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3.874 × 109 J | ||||
| Robertson, Robert and Garner, William Edward. Calorimetry of high explosives. Proceedings of the Royal Society of London. Series A. Vol. 103 No. 723 (1923): 539–555. | [14 values reported across 3 tables. Average value: 962.929 calorie/gram.] | 4.029 × 109 J | ||||
| Taylor, G.I. Dynamics of a mass of hot gas rising in air. United States Atomic Energy Commission (1945). | "Example 1: Explosion of ton of TNT M = 106, E = 1000 calories per gram, ρ = .0013 grams/cm3, …" | 4.184 × 109 J | ||||
| The effects of nuclear weapons. Los Alamos Scientific Laboratory. (1950): 13. | "The energy release of such a bomb is approximately equivalent to that of 20 kilotons, i. e., 20,000 tons, of TNT, and since the energy equivalent of a ton of TNT is taken to be 109 calories, the energy release of the nominal atomic bomb is 2 × 1013 calories." | 4.184 × 109 J | ||||
| The effects of nuclear weapons, revised edition. United States Atomic Energy Commission (1962): 14. | "The calculations are based on an accepted, although somewhat arbitrary, figure of 1012 calories as the energy released in the explosion of this amount of TNT." | 4.184 × 109 J | ||||
| National Materials Advisory Board. Treatment and disposal of high-energy materials. Report AD-764 534. National Technical Information Service (NTIS), US Department of Commerce (1973): | "The heat of combustion of TNT is variously quoted at values between 800 and 1,000 calories per gram, while most common solid or liquid fuels yield between 6,000 and 11,000 calories per gram." | 3.347 × 109 J to 4.184 × 109 J | ||||
| Bretherick, L. Handbook of Reactive Chemical Hazards. 3rd ed. Boston, MA: Butterworths, 1985., p. 661 as cited in 2,4,6-Trinitrotoluene. Hazardous Substances Data Bank (HSDB). National Institutes of Health. | "Heat of decomposition: 5.1 kJ/g" | 5.1 × 109 J |
The heat of detonation of TNT was first measured in the early 20th century and found to be around 900–1,000 calories per gram. Scientists and engineers working on the first nuclear bombs in the 1940s decided to round this number to 1,000 and multiply it by 106 (the number of grams in a metric ton). The resulting quantity was adopted as a convenient way to describe the explosive potential of these new weapons. The 1960s saw the creation of the International System of Units (SI) and the fading out of the calorie in favor of the joule as the preferred unit of energy. With 4.184 joules for every 1 calorie, this gives us…
| 1,000 | calorie/gram TNT | |||
| × | 1,000,000 | gram/ton | ||
| × | 4.184 | joule/calorie | ||
| = | 4,184,000,000 | joule/ton TNT | ||
| = | 4.184 × 109 | joule/ton TNT | ||
| = | 4.184 | gigajoule/ton TNT |
This is the value used to describe the explosive power of nuclear weapons (usually in kilotons and megatons). It's a convention, but it isn't realistic. It was always meant to be a nice, round number (in calories, anyway) to make mental calculations easier. The most reliable value for the "actual" energy seems to be the value reported by the National Institutes of Health: 5.1 kJ/g, which upscales to 5.1 GJ/t.
Editor's Supplement -- 2025