✳ NUCLEAR EFFECTSUNDERSTAND & PREPARE
London, United Kingdom51.5074° N · 0.1278° W
SCENARIO PREVIEWGEOGRAPHIC SCALE
EFFECT LAYERS RADIUS

Contours show thresholds, not hard boundaries.

N↑
EXPLOSIVE ENERGY418 TJ

1 kiloton = 4.184 terajoules

5 PSI BLAST RADIUS—

Significant building damage possible

AREA WITHIN 5 PSI—

Geometric area, not a casualty estimate

READING THE MAP

Blast scales with the cube root of yield. 8× the energy ≈ 2× the blast radius.

WIND & FALLOUT

Beyond the blast rings

READ THE EFFECTS

What the contours mean

Approximate · model v3.0

Real effects vary continuously. A contour is an estimated threshold, not a wall or a safe-zone boundary.

⌂
Preparedness starts with reliable information.

The circular blast rings do not show fallout or tell you whether a location is safe. In a radiation emergency: get inside, stay inside, and stay tuned to official instructions.

THE MAP, EXPLAINED

A nuclear bomb simulator for understanding scale

Nuclear Effects Explorer is a free educational tool for comparing nuclear blast radius, fireball size, thermal energy and idealised fallout on a real map. It models one detonation at a time, with source-linked assumptions rather than a prediction of an actual event.

Nuclear blast and fallout questions

What is the blast radius of a nuclear bomb?

There is no single nuclear bomb radius. Fireball, blast overpressure, thermal radiation and fallout describe different effects. In this tool’s idealised 100 kt surface-burst calculation, the 5 psi blast radius is about 2.05 km and the 1 psi radius about 5.53 km. These are model reference distances, not safe-zone boundaries.

What does this nuclear bomb simulator show?

It maps approximate pressure contours, the maximum fireball envelope and a simplified thermal-energy threshold. Choose a surface burst or a fixed-reference airburst, compare yields, and optionally explore idealised surface-fallout contours with manual wind inputs. It does not model prompt radiation, real weather, casualties or evacuation routes.

Is the nuclear fallout map a real-time forecast?

No. The fallout map uses idealised dimensions from Glasstone and Dolan, a single effective wind and an assumed fission fraction. It has no live weather feed, radiation sensors or event data. Smooth contours cannot predict actual contamination, hot spots or where people are safe.

How far can nuclear fallout travel?

Fallout can extend well beyond the blast-affected area. Its distribution depends on the explosion, particle sizes, winds at different heights, precipitation and the ground surface. There is no universal fallout radius; this tool’s plume is a teaching model, not a forecast.

Can I use this map to find a safe distance?

No. The tool cannot assess a real event, shielding, shelter conditions, fires or actual radiation exposure. In a radiation emergency, follow official alerts and local instructions. The CDC’s core guidance is to get inside, stay inside and stay tuned.

Is Nuclear Effects Explorer free to use?

Yes. The educational simulator runs in your browser without an app download or payment. You can browse places, compare yields, save views on your device, copy scenario links and export a summary.

Sources: Glasstone & Dolan, chapter III, chapter IX and CDC radiation-emergency guidance. Model notes last updated 31 October 2026.

THE SCIENCE BEHIND THE SCENE

Physics, with its limits visible.

This explorer models a surface bursts or a fixed-reference airburst in a standard sea-level atmosphere, for yields from 1 to 10,000 kilotons. It is an independent educational project inspired by NUKEMAP.

Blast overpressure

Ground-range estimates use the surface-burst curve fit documented in the Nuclear Bomb Effects Computer (CEX-62.2), equation 2.5, with cube-root yield scaling:

r(km) = 1.609344 × W^(1/3) × 10^(−0.1307982 − 0.6836211x + 0.1091296x² − 0.0167348x³)
x = log₁₀(pressure in psi); W = yield in kt

These are idealised peak overpressure contours, not guaranteed damage boundaries. Terrain, shielding, building construction and atmospheric conditions are not resolved. The airburst option uses a fixed scaled reference height, not a height optimisation. Its pressure contours use the Brode reflected-blast fit adapted from the MIT-licensed glasstone library.

Fireball & thermal energy

Maximum fireball radius is estimated as 0.0792449 × W^0.4 km for surface bursts or 0.0609611 × W^0.4 km for the airburst reference. The thermal contour uses a simplified point-source energy budget: 18% effective partition for contact surface bursts, 35% for the airburst reference, fixed 70% transmission and a 10 cal/cm² threshold. Airburst ground range is projected from slant range. The aloft fireball ring is its maximum horizontal envelope projected onto the map, not ground contact. It ignores atmospheric path variation, obstructions, clouds, pulse duration and Earth curvature. It is not a burn or ignition prediction; thermal estimates become particularly uncertain at large yields.

What is not modelled

Prompt ionising radiation, EMP, fires, real weather and casualties are not modelled. Fallout is an optional idealised textbook reference, not an incident forecast. Surface bursts can generate substantial radioactive fallout beyond the displayed rings. The contours are not shelter recommendations, evacuation zones or a forecast of an actual incident.

Sources & implementation

Model v3.0: surface-burst and fixed-airburst reference calculations, with optional idealised surface fallout. Thermal energy uses the approximate surface-burst fraction discussed in Glasstone & Dolan §7.101; a fixed transmission factor is an illustrative assumption. This is not a validated burn-distance model.

For education, not emergency planning. This simplified model has not been independently validated.

DOCUMENTED YIELD REFERENCES

Yield references, with their sources.

Supplied estimates are unverified. The additional international list was provided by the site owner. It mixes warheads, delivery systems and historical tests. Its ranges should not be treated as confirmed capabilities.

CountrySupplied nameSupplied yield

The supplied W88 value is 475 kt; the separately sourced FAS (2025) estimate below is 455 kt. W76 yields depend on variant. North Korean and other estimates may not correspond to a verified deliverable warhead. No conversion from a test yield to a missile yield is assumed.

Tsar Bomba (50 Mt) is reference-only: it exceeds this model’s 10 Mt ceiling. The 0.5 kt Nasr range endpoint is below the 1 kt model minimum; its 5 kt endpoint can be explored.

Sourced US examples

These examples are public estimates from the Federation of American Scientists’ United States nuclear weapons, 2025, table 1 (p. 54). They are reference values, not claims about current loadouts. Each preset models one warhead, using the selected burst model.

Delivery systemWarheadEstimated yield
Trident II D5/LEW76-28 kt
Trident II D5/LEW76-190 kt
Trident II D5/LEW88455 kt
Minuteman IIIW87300 kt
Minuteman IIIW78335 kt
AGM-86B air-launched cruise missileW80-15–150 kt

For W80-1, presets provide the reported lower and upper yield settings. Estimates and variants differ; avoid treating a missile name as one fixed yield. This is a selection of documented US examples, not a complete global inventory.

Read the FAS source report ↗

Historical comparison yields (Hiroshima approximately 15 kt and Nagasaki approximately 21 kt) describe energy only. Their actual detonations were airbursts; these presets do not reconstruct those events.
PREPAREDNESS BASICS

Get inside. Stay inside. Stay tuned.

These are the CDC’s core principles for a radiation emergency, including a nuclear detonation. Follow instructions from the authorities where you are.

01

Get inside a building

Go to the nearest building promptly. A basement or the middle of a brick or concrete building can offer better protection. Cars offer poor protection from radioactive material.

02

Stay inside and follow instructions

Keep away from exterior walls and windows where possible. Do not use these blast rings to decide when to leave shelter: fallout can extend well beyond them. Follow official shelter and evacuation instructions.

03

Stay tuned to official information

Have a way to receive emergency updates, such as a battery-powered or hand-crank radio. Local authorities will give instructions as information becomes available.

CDC: Safety guidelines in a radiation emergency ↗

UK Government: Prepare for emergencies ↗

General educational guidance. These maps do not predict fallout, identify safe areas, or replace local emergency advice.
START EXPLORING

A clearer view of scale.

  1. Choose a location. Use the offline geographic directory, type coordinates, search online, or place the origin on the map.
  2. Set a yield. Use a sourced reference, a clearly labelled supplied estimate, or a custom value from 1 to 10,000 kt.
  3. Read each effect. Toggle contours and open Effect details. The thermal layer is an illustrative energy calculation.
  4. Compare and measure. Compare two yields at the same point, or use the ruler for straight-line geographic distance.
  5. Keep a record. Save a view on this device, copy a scenario link, export CSV, or print a summary.

No sign-in is needed inside the app. Hosting access still applies. Saved views and checklists use your browser’s local storage; location search sends your query to Photon and map requests go to Esri.

Model coverage: surface or fixed-reference airburst pressure, fireball envelope, simplified thermal-energy contour and optional idealised surface fallout. No live weather, prompt radiation, population or casualty model.

SAVE THIS SCENARIO

Your scenario link

Copy this link to reopen the same location, yield and effect layers. The site’s existing access permissions still apply.

HOW TO READ WIND & FALLOUT

Wind direction is only part of the picture.

“From” points upstream

A wind from the west blows toward the east. This guide rotates the idealised pattern toward the downwind direction. Effective wind represents motion across the cloud’s height; it is not a local surface-wind observation.

Use the controls as a teaching model

The base table assumes a 15° shear reference. Wind speed is limited to the source’s 8–45 mph range. Length follows the approximate wind factor in §9.97. Width and upwind distance are held fixed under §9.98’s approximation. Fission fraction rescales the rate labels under §9.94, not the geometry. It is a scenario assumption, not a known property inferred from the weapon name.

H+1 does not mean “arrives in one hour”

A unit-time reference rate expresses deposited fallout at a normalised one-hour reference. Actual fallout can arrive much later. These shapes do not show a moving cloud, arrival times, cumulative dose or shelter exposure.

The smooth plume is idealised

Table 9.93 gives downwind length and widths, not a complete deposition field. The envelope is reconstructed to illustrate those dimensions. Rain, wind shear, terrain, particle settling, buildings and surface roughness can change the pattern substantially, including hot spots and multiple directions.

Why airburst mode hides it

The fallout approximation is for contact surface bursts. It is not applied to the fixed airburst whose fireball remains aloft. This does not imply zero radiation or zero global fallout from an airburst.

Read the source: Table 9.93 and §§9.94–9.100 ↗

Use official alerts and local instructions in an emergency. This view cannot identify safe areas or evacuation routes.