Nuclear Blast Radius Map: See a Bomb's Effects at True Scale

The Nukes tool in TrueSize draws the estimated reach of a nuclear detonation as rings on the map, so you can see how far each effect would extend over a place you know. It includes 29 weapon presets, from the tiny Davy Crockett to the 50-megaton Tsar Bomba, and a custom yield from 0.001 to 100,000 kilotons. It is an educational tool built on published government effects methods.

Blast, thermal and radiation rings for one detonation, drawn at true scale.

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How to show a blast on the map

1. Open the Fun tab of the ribbon and click Nukes.
2. Choose the Burst type: Airburst or Surface burst. For a surface burst you can also set the Fallout wind speed in km/h.
3. Pick a weapon from the list, or type a Custom yield, choose kt or Mt, and click Show on map.
4. Click the map where you want the detonation. A banner reads "Click or tap the map to place" followed by the weapon name.
5. The rings appear. Use Change blast to pick another weapon, Hide fallout or Show fallout to toggle the plume, and Back to my spot to return to the place you chose.

The weapon list. Sort it by Power or Year.

What the rings mean

Each ring shows the estimated reach of one effect for a single detonation in clear weather.

Ring	What it shows
Fireball	The fireball at its largest; anything inside is exposed to extreme heat
Heavy blast (20 psi)	Heavy concrete buildings are severely damaged or demolished; few people survive
Radiation (500 rem)	Without medical treatment, half or more of the people exposed die within weeks
Buildings collapse (5 psi)	Most residential buildings collapse; injuries are universal and deaths widespread
3rd-degree burns	Burns through all layers of exposed skin; often fatal without care
Windows break (1 psi)	Windows shatter; many people are injured by flying glass
Fallout plume	Dose rate one hour after the burst, carried downwind (surface bursts only)

The effects are different for every yield. In general, the light-damage and burn rings grow much larger than the fireball, which is why a large weapon affects an area far bigger than most people expect.

Airburst or surface burst

• Airburst: the weapon explodes above the ground. For airbursts TrueSize uses a burst height chosen to maximize the 5 psi blast ring. This produces little local fallout, so no plume is drawn.
• Surface burst: the weapon explodes at ground level. This adds a fallout plume downwind, shaped by the wind speed you set (the default is 24 km/h). The wind direction is shown on the map as "Wind toward" a compass angle.

Notable presets

Weapon	Yield	Year	Note
Davy Crockett	0.02 kt	1962	Smallest US warhead, now retired
Little Boy	15 kt	1945	Used in war on Hiroshima
Fat Man	21 kt	1945	Used in war on Nagasaki
Trinity	24.8 kt	1945	First nuclear test
W76-1	90 kt	2008	Trident II warhead, in service
W88	475 kt	1989	Trident II warhead, in service
B83	1,200 kt	1983	Largest US bomb in service today
Ivy Mike	10,400 kt	1952	First hydrogen bomb test
Castle Bravo	15,000 kt	1954	Test at Bikini Atoll
Tsar Bomba	50,000 kt	1961	Largest weapon ever detonated
Tsar Bomba, full design	100,000 kt	1961	Never built

Each preset is labeled Used in war, Test, In service, Retired or Never built. Where a real test was underground, the rings show the same yield above ground, and the dialog says so. The full list also includes warheads and tests from several countries; each entry cites its sources.

Compare two weapons

Open Nukes again, pick another weapon and click the map: both blasts stay on the map, so you see them at the same scale. The comparison of the smallest wartime weapon with the largest test ever is on the Tsar Bomba vs Little Boy page.

Tsar Bomba (50 Mt) and Little Boy (15 kt) at the same scale.

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The casualty estimate

TrueSize also shows People living inside the rings and an Estimated casualties section with a range of deaths and injuries. The estimate combines two published methods and reports both as a range:

• Blast only: shares of people killed and injured in each overpressure zone, from the US Office of Technology Assessment, The Effects of Nuclear War (1979).
• Including mass fires: the same blast rules outside a fire zone, but everyone inside the fire zone counts as a fatality, following T. A. Postol's 1986 analysis of firestorms.

The number of people inside each ring comes from the GHS-POP 2025 population grid of the European Commission's Joint Research Centre.

This is an estimate, not a prediction. The models leave out fallout, later deaths, shelter, warning time and the time of day, so real numbers could be lower or higher. TrueSize shows them only to give a sense of scale.

Sources and method

The ring distances use the public US government methods in Glasstone and Dolan, The Effects of Nuclear Weapons (1977), and Fletcher and others (1963), with fallout scaling from US civil-defense research reports. The dialog lists the effects sources under Sources, and every weapon entry links to references such as Wikipedia articles on the weapon or test.

Examples to try

• Load Little Boy on your own city to see the 1945 scale.
• Compare Castle Bravo with Ivy Mike, two early hydrogen-bomb tests.
• Try Custom yield at 100 kt to see a modern strategic warhead size.
• Read the Tsar Bomba vs Little Boy comparison.

Where it works

The Nukes tool works on the web and in the TrueSize mobile app. It is not available while a planet is shown.

Related

• Move and compare regions
• Population radius tool
• Distance and bearing
• Map styles

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Next: Map styles and skins