Little Boy vs FOAB (Father of All Bombs)
Nuclear weapon side-by-side comparison
Little Boy
USA · 1945 · pure fission
15 kt
Hiroshima bomb.
FOAB (Father of All Bombs)
Russia · 2007 · conventional
44 tons TNT
Most powerful non-nuclear bomb - Thermobaric.
Verdict
The Little Boy is 341× more powerful than the FOAB (Father of All Bombs) by yield. Both weapons are described in detail below, with side-by-side blast and thermal radii, casualty estimates at a reference urban density, and historical context.
Blast & thermal effects (air burst)
| Effect zone | Little Boy | FOAB (Father of All Bombs) |
|---|---|---|
| Yield | 15 kt | 44 tons TNT |
| Fireball radius | 0.43 km | 0.04 km |
| Severe blast (20 PSI) | 1.18 km | 0.17 km |
| Moderate blast (5 PSI) | 2.52 km | 0.37 km |
| Light blast (1 PSI) | 7.16 km | 1.05 km |
| 3rd-degree thermal burns | 2.03 km | 0.19 km |
| 2nd-degree thermal burns | 3.64 km | 0.33 km |
Casualty estimate (dense urban target)
Estimated immediate fatalities if each weapon air-bursts over a city center with a population density of about 8,000 per km² (representative of dense urban cores like Manhattan or central Paris):
Real casualties depend strongly on time of day, sheltering, weather, and altitude of detonation. See the methodology page for the underlying formulas.
Hiroshima reference
The Hiroshima bomb (Little Boy) had a yield of approximately 15 kilotons. The Little Boy is 1× more powerful than the Hiroshima bomb. The FOAB (Father of All Bombs) is 340.9× smaller.
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FAQ
Is the Little Boy bigger than the FOAB (Father of All Bombs)?
Yes. The Little Boy (15 kt) is 340.9× more powerful than the FOAB (Father of All Bombs) (44 tons TNT).
What is the blast radius of the Little Boy compared to the FOAB (Father of All Bombs)?
For an air burst, the Little Boy produces a 5 PSI moderate-blast radius of 2.52 km, versus 0.37 km for the FOAB (Father of All Bombs). Severe blast (20 PSI): 1.18 km vs 0.17 km. 3rd-degree thermal burns: 2.03 km vs 0.19 km.
How many people would die from a Little Boy compared to a FOAB (Father of All Bombs)?
Detonated over a typical dense city center (8,000 people/km²), the Little Boy would cause an estimated 96,377 immediate fatalities. The FOAB (Father of All Bombs) would cause an estimated 2,053. Real numbers depend on time of day, sheltering, weather, and altitude of detonation.
How do the Little Boy and FOAB (Father of All Bombs) compare to the Hiroshima bomb?
The Little Boy is 1× more powerful than the Hiroshima bomb (Little Boy, 15 kt). The FOAB (Father of All Bombs) is 340.9× smaller than the Hiroshima bomb.