B41
USA · 1960 · 25 megatons · thermonuclear (hydrogen bomb)
Overview
Most powerful US bomb ever deployed.
With a yield of 25 megatons[1], the B41 is 1,667× more powerful than the Hiroshima bomb. As a thermonuclear (hydrogen bomb) weapon, it derives its energy from a fission explosion that ignites fusion fuel, releasing on average roughly equal energy from fission and fusion. [2]
B41 Blast Effects
The table below shows the calculated radius of each effect zone for an air burst at optimum height. Values are scaling laws from The Effects of Nuclear Weapons (Glasstone & Dolan, 1977) and the published effects scaling table[3, 4].
| Effect zone | Radius (air burst) |
|---|---|
| Fireball radius | 3.50 km |
| Severe blast (20 psi) | 6.89 km |
| Moderate blast (5 psi) | 18.3 km |
| Light blast (1 psi) | 50.7 km |
| 3rd-degree thermal burns | 41.4 km |
| 2nd-degree thermal burns | 47.7 km |
| 1st-degree thermal burns | 57.2 km |
All radii assume an air burst at optimum height and are 1-D ground-distance estimates from the detonation point. Real-world effects depend on terrain, weather, and building construction. Casualty and fallout estimates are not shown pending a verified population and fallout model.
Run the B41 on a City
Use the interactive simulator to detonate the B41 on any city worldwide. Click any location on the map to see the fireball, blast, and thermal radii (air burst at optimum height) overlaid on real geography.
🎯 Simulate B41Related Weapons
FAQ
How big is the B41 blast radius?
In an air burst at optimum height, the B41 produces a fireball roughly 3.50 km in radius and a 5 psi moderate-blast zone of about 18.3 km — the area in which most residential buildings would collapse. The 1 psi light-damage radius extends to roughly 50.7 km, where windows shatter.
What is the yield of the B41?
The B41 has a yield of 25 megatons of TNT equivalent. That is 1,667× more powerful than the Hiroshima bomb.
Is the B41 bigger than the Hiroshima bomb?
The Hiroshima bomb (Little Boy) had a yield of approximately 15 kilotons. The B41 at 25 megatons is 1,667× more powerful than the Hiroshima bomb.[5]
What thermal burn radius does the B41 produce?
In an air burst at optimum height, thermal radiation from the B41 can cause 3rd-degree burns out to roughly 41.4 km, 2nd-degree burns to 47.7 km, and 1st-degree burns to 57.2 km.
Sources
- 1.Source: Nuclear Weapon Archive (Carey Sublette), Complete List of All U.S. Nuclear Weapons (last changed 30 Mar 2023) — retrieved Oct 2026
- 2.Source: US DoD & ERDA (Glasstone & Dolan), via Atomic Archive, The Effects of Nuclear Weapons, 3rd ed. (1977), Chapter 1 — retrieved Oct 2026
- 3.Source: U.S. DoD / DOE (Glasstone & Dolan, via Atomic Archive), The Effects of Nuclear Weapons, 3rd ed. (1977) §2.127 — retrieved Oct 2026
- 4.Source: Wikipedia, Effects of nuclear explosions — scaling-law table — retrieved Oct 2026
- 5.Source: US DOE / NNSA Nevada Field Office, United States Nuclear Tests, July 1945 through September 1992 (DOE/NV-209 Rev. 16, Sep 2015), NNSS publication library — retrieved Oct 2026