Castle Bravo
USA · 1954 · 15 megatons · thermonuclear (hydrogen bomb)
Overview
Most powerful US nuclear test.
With a yield of 15 megatons, the Castle Bravo is 1,000× more powerful than the Hiroshima bomb. As a thermonuclear (hydrogen bomb) weapon, it derives its energy from a fission primary that ignites a much larger fusion secondary stage.
Castle Bravo Blast Effects
The table below shows the calculated radius of each effect zone for an air burst (optimal altitude, maximum blast spread) and a surface burst (ground level, with massive radioactive fallout). Formulas are scaling laws from The Effects of Nuclear Weapons (Glasstone & Dolan, 1977).
| Effect zone | Air burst | Surface burst |
|---|---|---|
| Fireball radius | 6.79 km | 5.43 km |
| Severe blast (20 PSI) | 11.51 km | 6.33 km |
| Moderate blast (5 PSI) | 24.60 km | 13.53 km |
| Light blast (1 PSI) | 69.98 km | 38.49 km |
| 3rd-degree thermal burns | 34.54 km | 20.72 km |
| 2nd-degree thermal burns | 61.86 km | 37.11 km |
| Lethal fallout zone | minimal | ~561.8 km |
All values are 1-D ground-distance estimates from the detonation point. Real-world effects depend on terrain, weather, and building construction.
Run the Castle Bravo on a City
Use the interactive simulator to detonate the Castle Bravo on any city worldwide. Click any location on the map to see the fireball, blast, and thermal radii overlaid on real geography with population-density-based casualty estimates.
🎯 Simulate Castle BravoRelated Weapons
FAQ
How big is the Castle Bravo blast radius?
In an air burst, the Castle Bravo produces a fireball roughly 6.79 km in radius and a 5 PSI moderate-blast zone of about 24.60 km — the area in which most residential buildings would collapse. The 1 PSI light-damage radius extends to roughly 69.98 km, where windows shatter.
What is the yield of the Castle Bravo?
The Castle Bravo has a yield of 15 megatons of TNT equivalent. That is 1,000× more powerful than the Hiroshima bomb.
Is the Castle Bravo bigger than the Hiroshima bomb?
The Hiroshima bomb (Little Boy) had a yield of approximately 15 kilotons. The Castle Bravo at 15 megatons is 1,000× more powerful than the Hiroshima bomb.
What thermal burn radius does the Castle Bravo produce?
Thermal radiation from the Castle Bravo can cause 3rd-degree burns out to roughly 34.54 km and 2nd-degree burns out to 61.86 km in an air burst. Surface bursts reduce these radii by approximately 40 percent due to ground absorption.