Chagai
Pakistan · 1998 · claimed up to 40 kt (seismic estimates about 9 kt) · fission (claimed boosted)
Overview
First Pakistani nuclear test; claimed up to 40 kt (seismic estimates about 9 kt).
With a claimed yield of up to 40 kt (seismic estimates about 9 kt)[1], the Chagai-I derives its energy from nuclear fission of uranium; Pakistan says the devices were boosted. [2, 1]
Chagai-I 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 | 0.27 km |
| Severe blast (20 psi) | 0.77 km |
| Moderate blast (5 psi) | 2.14 km |
| Light blast (1 psi) | 5.90 km |
| 3rd-degree thermal burns | 3.30 km |
| 2nd-degree thermal burns | 4.21 km |
| 1st-degree thermal burns | 5.49 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 Chagai-I on a City
Use the interactive simulator to detonate the Chagai-I 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 Chagai-IRelated Weapons
FAQ
How big is the Chagai-I blast radius?
In an air burst at optimum height, the Chagai-I produces a fireball roughly 0.27 km in radius and a 5 psi moderate-blast zone of about 2.14 km — the area in which most residential buildings would collapse. The 1 psi light-damage radius extends to roughly 5.90 km, where windows shatter.
What is the yield of the Chagai-I?
Pakistan claimed a yield of up to 40 kt. Independent seismic estimates put it near 9 kt (roughly 5 to 20 kt), below the 15 kt Hiroshima bomb.[1]
Is the Chagai-I bigger than the Hiroshima bomb?
Only by Pakistan's claim of up to 40 kt. Seismic estimates of about 9 kt make it smaller than the 15 kt Hiroshima bomb.[5, 1]
What thermal burn radius does the Chagai-I produce?
In an air burst at optimum height, thermal radiation from the Chagai-I can cause 3rd-degree burns out to roughly 3.30 km, 2nd-degree burns to 4.21 km, and 1st-degree burns to 5.49 km.
Sources
- 1.Source: Nuclear Weapon Archive (Carey Sublette), Pakistan's Nuclear Weapons Program - 1998: The Year of Testing — 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