TNT Equivalent Calculator
Convert any amount of energy to kilograms of TNT, convert TNT mass back to energy, compare explosives with TNT equivalence factors, and estimate compressed-gas pressure-vessel burst energy — all on the standard scale where 1 kg of TNT = exactly 4.184 MJ.
Convert energy to TNT equivalent
Convert TNT mass to energy
Convert explosive mass to TNT equivalent
The TNT equivalence (relative effectiveness) factor multiplies the explosive mass to give the mass of TNT releasing the same energy.
Pressure-vessel burst: energy → TNT equivalent
The formula
For other explosives: mTNT = mexplosive × RE factor (for example RDX: × 1.6, PETN: × 1.66, ANFO: × 0.82). For a compressed-gas pressure vessel (simplified): E ≈ Pgauge × V, then convert E to TNT equivalent as above.
Real-world reference events
Put any result in perspective with well-known energy releases, all approximate:
| Event | TNT equivalent |
|---|---|
| M67 hand grenade | 0.2 kg |
| Typical lightning bolt (~1 GJ) | 239 kg |
| MOAB, GBU-43/B (8.5 t of H6 explosive) | 11 t |
| Hiroshima, Little Boy (1945) | 15 kt |
| Nagasaki, Fat Man (1945) | 21 kt |
| Castle Bravo nuclear test (1954) | 15 Mt |
| Tsar Bomba (1961) | 50 Mt |
The calculator shows the nearest reference automatically for every result. Note that the MOAB figure is the TNT equivalent of its 8.5-ton H6 fill, not the fill weight itself.
TNT equivalence factors for common explosives
| Explosive | RE factor (kg TNT per kg) |
|---|---|
| TNT (reference) | 1.00 |
| ANFO | 0.82 |
| TATB | 1.16 |
| Tetryl | 1.25 |
| Composition B | 1.33 |
| RDX | 1.60 |
| HMX | 1.60 |
| PETN | 1.66 |
Relative effectiveness (RE) factors normalize the energy content of an explosive to TNT. They describe total energy, not blast behaviour: confinement, geometry and release rate still decide real-world effects.
Scope boundary
This is an educational energy-conversion tool. It converts between energy units and TNT-equivalent mass — the same kind of arithmetic as converting joules to kilowatt-hours. It contains no information about manufacturing, handling or detonating explosives, and the simplified pressure-vessel estimate is not a substitute for qualified engineering analysis.
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Frequently asked questions
What is TNT equivalent?
TNT equivalent is a way to express any amount of energy as the mass of TNT that would release the same amount of energy. It lets engineers, scientists and students compare energies from completely different sources — batteries, fuels, lightning, compressed gas — on one familiar scale, from grams up to megatons.
How many megajoules are in 1 kg of TNT?
By the standard convention used in this calculator, 1 kg of TNT releases exactly 4.184 megajoules (4,184,000 joules). This value comes from the thermochemical energy of TNT and is the reference used in blasting engineering, so 1 metric ton of TNT equals exactly 4.184 gigajoules.
How do I convert kWh to kilograms of TNT?
Divide the energy by 4.184 MJ per kg of TNT. Since 1 kWh equals 3.6 MJ, 1 kWh equals 3.6 / 4.184 = 0.8604 kg of TNT. For example, 1 MWh (1,000 kWh) equals 3,600 / 4.184 = 860.42 kg of TNT, and a typical 60 kWh electric-car battery holds about 51.6 kg of TNT equivalent.
What is the TNT equivalence factor of RDX?
RDX has a TNT equivalence (relative effectiveness) factor of 1.6, meaning 1 kg of RDX releases about the same energy as 1.6 kg of TNT. The calculator applies this factor automatically: multiply the explosive mass by 1.6 to get kilograms of TNT equivalent.
What are the TNT equivalence factors of PETN and ANFO?
PETN has a factor of 1.66, so 1 kg of PETN is about 1.66 kg of TNT, and ANFO has a factor of 0.82, so 1 kg of ANFO is about 0.82 kg of TNT. The explosives table in this calculator also includes TNT (1.00), Composition B (1.33), HMX (1.60), TATB (1.16) and Tetryl (1.25).
How is the TNT equivalent of a pressure vessel burst calculated?
A common first-order engineering estimate treats the stored energy of the compressed gas as E = P x V (gauge pressure times volume) and divides by 4.184 MJ per kg. For example, a 50-litre cylinder at 200 bar gauge stores 20 MPa x 0.05 m3 = 1 MJ, about 0.239 kg of TNT equivalent. The calculator does this automatically, but it is a simplified educational estimate, not a safety assessment.
What is the TNT equivalent of a hand grenade?
A typical fragmentation hand grenade such as the M67 is roughly equivalent to 0.2 kg of TNT. For comparison, that is about 0.837 MJ of energy, or 0.232 kWh — roughly the energy stored in a small laptop battery.
What is the TNT equivalent of the MOAB?
The GBU-43/B MOAB carries about 8.5 tons of H6 explosive, which is roughly equivalent to 11 tons of TNT. It is one of the largest conventional bombs ever deployed, yet still about 1,400 times smaller than the 15-kiloton Hiroshima bomb.
What was the TNT equivalent of the Hiroshima bomb?
The Little Boy bomb dropped on Hiroshima in 1945 had a yield of about 15 kilotons of TNT — 15,000 tons, or 15 million kilograms. That equals 62,760 gigajoules (62.76 terajoules) of energy, since each ton of TNT is exactly 4.184 GJ.
What was the yield of the Tsar Bomba in TNT equivalent?
The Soviet Tsar Bomba, detonated in 1961, had a yield of 50 megatons of TNT — 50 billion kilograms of TNT equivalent, about 209 exajoules. It remains the largest human-made explosion in history, roughly 3,300 times the yield of the Hiroshima bomb.
Is TNT equivalent the same as actual explosive power?
Not exactly. TNT equivalent normalizes total energy content, but real blast damage also depends on how fast the energy is released, confinement, geometry and distance. Two sources with the same TNT equivalent can produce very different effects — a slow-burning fuel fire and a detonating explosive release energy at completely different rates.
Why is TNT used as the standard reference?
TNT is a well-characterized military explosive with a stable, reproducible energy release, and its energy content of 4.184 MJ per kg is a convenient reference. Blasting engineers have used it as the standard yardstick for over a century, so yields from fireworks to nuclear weapons are quoted in tons, kilotons and megatons of TNT.
Can I use this calculator for pressure-vessel safety assessments?
No. The pressure-vessel mode uses the simplified E = P x V estimate for education only. Real burst-energy analysis uses methods such as the Baker or Brode models, accounts for gas properties and vessel failure modes, and must be performed by a qualified pressure-systems engineer. Never use these numbers for design, inspection or safety decisions.
Does this calculator give instructions for making explosives?
No. It converts between energy units and TNT-equivalent mass — the same kind of unit conversion as joules to kilowatt-hours. It contains no information about manufacturing, handling or detonating explosives, and nothing here should be interpreted as guidance for any of that.
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