Nuclear Blast Radius Map by Yield
Six documented weapons are built in, from the 15 kt Hiroshima bomb to the 50 Mt Tsar Bomba, and the slider runs from 1 kiloton to 100 megatons. Because blast distance grows with the cube root of yield, the map is the quickest way to see why a thousandfold bigger bomb reaches only ten times farther.
10⁴ m · ≈ 10 km (blast rings) · MapLibre · Physics model
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Yield, burst height, rings
Why a bigger bomb is not proportionally bigger on the map
Blast overpressure scales with the cube root of yield. Go from 1 kiloton to 1 megaton, a thousandfold jump, and each pressure ring only reaches ten times farther, enclosing a hundred times the area. The presets make that visible: Hiroshima at 15 kt, Nagasaki at 21 kt, a modern tactical warhead at 50 kt, the W87 at 300 kt, the B83 at 1.2 Mt, and the Tsar Bomba at 50 Mt. The slider covers everything from 1 kt to 100 Mt, and a text field accepts any custom value.
Start with two presets
- Pick a city or tap the map to set ground zero.
- Load Hiroshima, then load the W87. The yield is twenty times higher, but the cube root of twenty is about 2.7, so every blast ring is only about 2.7 times wider.
- Load the Tsar Bomba. At 50 Mt its rings are roughly 3.7 times wider than the B83’s at 1.2 Mt, not forty times.
- Export the map once the rings tell the story you want to share.
What each ring measures
From the centre outward: the fireball; the 20 psi ring, where reinforced concrete fails; the 5 psi ring, where most houses collapse; the 1 psi ring, where windows break over a wide area. A separate ring marks the reach of third-degree burns from the heat flash, and for smaller yields a prompt-radiation ring marks an approximate 500 rem dose. Radii are given in kilometres and miles.
Airburst or surface burst
The optimum airburst height in this model is 230 metres times the cube root of the yield in kilotons, about 1.5 km for a 300 kt weapon. Detonating there spreads the 5 psi zone over the largest possible area and keeps the fireball off the ground, so little local fallout forms. A surface burst produces a larger fireball and digs a crater, but its blast rings are smaller, and it lofts contaminated debris downwind. The map draws the rings for either choice; it does not draw fallout, because fallout depends on wind and weather that no static map can know.
How the radii are computed
The overpressure rings follow the cube-root scaling in Glasstone and Dolan’s The Effects of Nuclear Weapons, the public reference behind most blast calculators. Fireball radius grows with roughly the 0.4 power of yield, the third-degree-burn radius with about the 0.41 power, and the 500 rem radius with about the 0.19 power, which is why radiation matters most for small weapons and blast for large ones. A population-density setting, from rural to dense city, only scales the number of people counted inside each ring.
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Questions about blast radius
What is the blast radius of a nuclear bomb?
There is no single number. Each effect has its own ring and its own scaling: for a 15 kt airburst the modeled 5 psi ring is about 1.8 km and the 1 psi ring about 4.4 km; at 1 Mt those grow to roughly 7.1 km and 18 km. The fireball, burn, and radiation rings all follow different curves.
How does blast radius scale with yield?
By the cube root. Multiplying the yield by 1,000, from 1 kt to 1 Mt, only multiplies each overpressure radius by 10. That is why a 50 Mt Tsar Bomba does not flatten fifty times more ground than a 1 Mt weapon: its blast rings are about 3.7 times wider.
Airburst or surface burst: which reaches farther?
An optimum-height airburst spreads blast and heat over a larger area and leaves little local fallout. A surface burst produces a larger fireball and a crater, but its blast rings are smaller, and it lofts contaminated debris that this map does not draw.
How far does the prompt radiation reach?
The 500 rem ring scales slowly with yield, about the 0.19 power, so it matters most for small weapons. For yields of a few hundred kilotons and up, the blast and thermal rings extend well past it. Delayed fallout is a separate, weather-driven hazard outside this model.
What do the 20, 5, and 1 psi rings mean?
They are overpressure thresholds from Glasstone and Dolan's The Effects of Nuclear Weapons: around 20 psi, reinforced concrete structures fail; around 5 psi, most residential buildings collapse; around 1 psi, windows break over a wide area and glass injuries become common.
How accurate is this nuclear blast radius map?
It applies public scaling laws to an idealized flat target in clear air. Terrain, weather, building density, and actual burst height all change real outcomes, so the rings are for understanding scale and history, not for planning.
Educational estimates from public scaling laws on an idealized flat target. Fallout, terrain, and weather are not modeled.