What If UniverseOpen the simulatorNuke simulator
Choose a real weapon, from the 15 kiloton Hiroshima bomb to the 50 megaton Tsar Bomba, and drop it anywhere on Earth. Fire as many as you like and watch the fallout drift with the wind.
Try it now: free, in your browser
Blast, heat and fallout
Each warhead comes down from space and detonates as an airburst or a ground burst. The simulator draws the fireball, the heavy and light blast rings, the radius of third-degree burns and the mushroom cloud, and counts the people killed and injured inside them using real population data.
Ground bursts suck up dirt and send radioactive fallout downwind. The fallout is carried by a moving wind field and washed out by rain, so it can cross borders and reach other countries hours or days later. The fallout map shows the dose people would receive, and the counter shows how many would fall sick or develop cancer later.
Hit enough cities and the smoke from burning cities rises into the stratosphere. The planet cools, harvests fail and famine follows. This nuclear winter builds up in the simulator as you fire more weapons.
Where the numbers come from
Weapon effects follow Glasstone and Dolan, The Effects of Nuclear Weapons. Casualty rates follow the US Office of Technology Assessment (1979). Nuclear winter cooling and famine follow Xia et al. (2022). Population comes from the GHSL grid.
Questions
How far does a nuclear blast reach?
It depends on the yield. A 15 kiloton bomb like Hiroshima destroys most buildings within about 1.5 km; a 1 megaton warhead within about 7 km; the 50 megaton Tsar Bomba within about 25 km, with burns much further out.
Where would fallout go?
Downwind. The simulator uses a moving wind field, so the plume follows the weather of the day and can reach neighbouring countries. Rain brings it down faster where it falls.
How many bombs cause a nuclear winter?
Burning cities matter more than the number of bombs. In the simulator, a few dozen large warheads on big cities put enough soot into the sky to cool the Earth by several degrees and cause famine worldwide.
All numbers in the simulator are rough estimates meant to show what could happen, not predictions.