Convert between energy (joules, kWh, calories) and TNT equivalent mass. Includes blast radius estimation and explosion reference table.
The TNT equivalent is a standard way to express the energy released by an explosion, impact, or other energetic event. One kilogram of TNT releases 4.184 megajoules (1 million calories) — this well-characterized value makes it a universal yardstick for comparing wildly different energy sources.
Nuclear weapons are measured in kilotons (kt) or megatons (Mt) of TNT equivalent. The Hiroshima bomb released about 15 kt (63 TJ); the Tsar Bomba delivered 50 Mt (210 PJ). But TNT equivalents apply far beyond weapons: asteroid impacts, volcanic eruptions, industrial explosions, and even everyday energy comparisons all use this scale.
The Hopkinson-Cranz blast scaling law relates overpressure radius to the cube root of charge weight, enabling quick blast damage estimates. At 1 psi overpressure (6.9 kPa), windows shatter; at 5 psi, buildings suffer structural damage; at 10 psi, reinforced concrete may fail. This calculator converts energy to/from TNT and estimates these blast zones.
Scientists, engineers, and journalists use TNT equivalents to communicate the scale of energetic events. This calculator provides instant conversion with physical context — blast zones and everyday energy comparisons make abstract numbers tangible.
This tool is designed for quick, accurate results without manual computation. Whether you are a student working through coursework, a professional verifying a result, or an educator preparing examples, accurate answers are always just a few keystrokes away.
E = m_TNT × 4.184 × 10⁶ J/kg. Blast radius (Hopkinson-Cranz): R = k × W^(1/3), where k ≈ 2.4 m/kg^(1/3) for 1 psi, 0.9 for 5 psi, 0.5 for 10 psi.
Result: 2.09 GJ, glass breakage at 19m, structural damage at 7.1m
500 kg TNT: E = 500 × 4.184 MJ = 2.09 GJ. Cube root scaling: 1 psi radius = 2.4 × 500^(1/3) = 2.4 × 7.94 = 19.1m for window breakage.
Use consistent units throughout your calculation and verify all assumptions before treating the output as final. For professional or academic work, document your input values and any conversion standards used so results can be reproduced. Apply this calculator as part of a broader workflow, especially when the result feeds into a larger model or report.
Most mistakes come from mixed units, rounding too early, or misread labels. Recheck each final value before use. Pay close attention to sign conventions — positive and negative inputs often produce very different results. When working with multiple related calculations, keep intermediate values available so you can trace discrepancies back to their source.
Enter the most precise values available. Use the worked example or presets to confirm the calculator behaves as expected before entering your real data. If a result seems unexpected, compare it against a manual estimate or a known reference case to catch input errors early.
TNT detonation energy is well-characterized (4.184 MJ/kg), stable, reproducible, and historically important — it became the standard calibration explosive for blast testing.
No. RDX, HMX, and CL-20 are 1.3-1.7× more powerful per kg. TNT is just the reference standard, not the strongest.
1 kiloton = 1000 metric tons = 10⁶ kg of TNT = 4.184 TJ of energy. The Hiroshima bomb was about 15 kilotons.
Hopkinson-Cranz scaling gives order-of-magnitude estimates for open-air, ground-level detonation. Real blast effects depend heavily on geometry, altitude, terrain, and confinement.
Yes — that's a common use. A gallon of gasoline contains about 0.03 kt of energy. A lightning bolt is roughly 0.24 kg TNT equivalent.
The 2020 Beirut port explosion was estimated at 500-1100 tons of TNT equivalent (from ~2750 tons of ammonium nitrate at ~42% TNT equivalence). Use this as a practical reminder before finalizing the result.