Trinity
USA · 1945 · 25 kilotons · pure fission
Overview
First nuclear test.
With a yield of 25 kilotons, the Trinity is 2× more powerful than the Hiroshima bomb. As a pure fission weapon, it derives its energy from nuclear fission of uranium or plutonium.
Trinity 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 | 0.53 km | 0.42 km |
| Severe blast (20 PSI) | 1.39 km | 0.77 km |
| Moderate blast (5 PSI) | 2.98 km | 1.64 km |
| Light blast (1 PSI) | 8.48 km | 4.66 km |
| 3rd-degree thermal burns | 2.51 km | 1.50 km |
| 2nd-degree thermal burns | 4.49 km | 2.69 km |
| Lethal fallout zone | minimal | ~43.5 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 Trinity on a City
Use the interactive simulator to detonate the Trinity 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 TrinityRelated Weapons
FAQ
How big is the Trinity blast radius?
In an air burst, the Trinity produces a fireball roughly 0.53 km in radius and a 5 PSI moderate-blast zone of about 2.98 km — the area in which most residential buildings would collapse. The 1 PSI light-damage radius extends to roughly 8.48 km, where windows shatter.
What is the yield of the Trinity?
The Trinity has a yield of 25 kilotons of TNT equivalent. That is 2× more powerful than the Hiroshima bomb.
Is the Trinity bigger than the Hiroshima bomb?
The Hiroshima bomb (Little Boy) had a yield of approximately 15 kilotons. The Trinity at 25 kilotons is 2× more powerful than the Hiroshima bomb.
What thermal burn radius does the Trinity produce?
Thermal radiation from the Trinity can cause 3rd-degree burns out to roughly 2.51 km and 2nd-degree burns out to 4.49 km in an air burst. Surface bursts reduce these radii by approximately 40 percent due to ground absorption.