The short answer
NUKEMAP is a free online map made by historian Alex Wellerstein that draws rough circles for a nuclear explosion's fireball, radiation, blast and heat, plus an estimated fallout plume for a ground burst. Its own FAQ calls the results back-of-the-envelope estimates that ignore buildings, terrain and weather, and its terms say it shouldn't be used for emergency planning. It is not a forecast and there is no official UK target list. What the circles do show is why official advice is to get inside a solid building fast, go to the middle, and stay in.
Why so many people are using it
Searches for "nukemap" in the UK rose sharply over the last 12 months, along with "nuclear bomb simulator" and "nuclear bomb map UK". If you've just dropped a pin on your town and found it hard to look at, that's a normal reaction. This page explains what you were looking at, and what it can't tell you.
What NUKEMAP is (and isn't)
NUKEMAP was created in February 2012 by Alex Wellerstein, a historian of nuclear weapons. It isn't a government tool. Its own FAQ is honest about its limits:
- The results are "back-of-the-envelope", "order of magnitude" estimates.
- It does not account for terrain, buildings that shield people, or weather.
- The numbers "might be too high" and "might also be too low".
- Its terms of use say it should not be used for emergency planning.
So it shows rough scale. It is not a prediction of what would happen, where, or to whom.
What the circles mean, in plain words
NUKEMAP lets you switch on several kinds of ring. These are the labels it uses, explained.
| Ring | Example NUKEMAP label | In plain words |
|---|---|---|
| Fireball | Fireball | The ball of fire itself. NUKEMAP's FAQ says what matters is whether it touches the ground: if it does, it's a ground burst, which makes local fallout. |
| Radiation | e.g. 500 rem | Radiation given off by the explosion itself. "rem" is a unit of radiation dose. |
| Blast | 20 psi (heavy damage), 5 psi (medium damage), 1 psi (light damage) | Blast pressure. The higher the psi, the stronger the blast and the closer to the centre. The 1 psi ring is the widest blast ring. |
| Heat | e.g. third-degree burns (50% probability) | How far the flash of heat could burn bare skin. |
| Fallout | Fallout contours | A rough plume shape downwind. Only for a ground burst. |
psi means pounds per square inch: a measure of blast pressure. NUKEMAP's FAQ says its casualty figures mainly use blast pressure as a stand-in for injuries, and don't allow for buildings shielding people.
Two things the map makes clear:
- The outer rings cover far more area than the inner ones. Most of the shaded map is in the lighter-damage and heat zones, not the centre.
- Shelter matters most in those outer zones. Ready.gov says that if you're warned and can't get inside, lie face down to protect exposed skin from heat and flying debris, then get into a solid building as soon as you can.
Want the official version? Our nuclear blast distances tool draws only the three damage zones from US government (FEMA) planning guidance, with what to do in each zone, and stores no location.
The fallout plume is the part to read carefully
NUKEMAP's FAQ says its fallout model:
- applies only to a ground burst, not an air burst (an air burst adds only a negligible amount of short-term local fallout)
- is a scaling model that gives a rough idea of the size of the contaminated area
- makes no attempt to model real wind conditions
So the direction of the plume on your screen is just the default setting. Real fallout would go wherever the wind went that day.
What official guidance says about fallout:
- Ready.gov says you'll usually have 10 minutes or more to find shelter before fallout arrives, and radiation levels drop quickly during the first 24 hours.
- The safest buildings have brick or concrete walls. Go to a basement or the middle of the building.
- Ready.gov says stay in for at least 24 hours unless told otherwise. UKHSA's radiation advice says one to two days, possibly longer.
Is my town a target?
No official UK source says. The National Risk Register 2026 says the government's scenario for a nuclear attack on the UK is held internally at a higher classification. Maps of "UK targets" online usually come from 1970s government papers released in 2014; Full Fact says they don't give any reliable picture of today. We explain this in where is safer from a nuclear attack?
What to do with this
The simulator can't tell you what will happen. It does show why the UK's advice is the same everywhere: go in, stay in, tune in.
- Pick your shelter room now: the middle of the building, fewest outside walls and windows. See which room is safest.
- Keep 3 days of water and food there or nearby.
- Keep a battery or wind-up radio to hear official instructions if power or phones are down.
- Read what to do if there's a nuclear attack warning, once, so you know the steps.
If the maps have left you feeling anxious, close the tab. This post on coping with worry about war may help.
What to buy
About these links: plain links to ordinary retailer pages. We may earn from some links in future; we don't now. We haven’t tested these and we don’t rank them: they are examples that were in stock when we checked. Prices change. Check what you already own first. Full kit list
Battery or wind-up FM radio
Look for: FM (Be Ready asks for FM; DAB as well is fine). Both a crank and ordinary batteries, so you have two ways to power it.
Bottled water
Look for: 3 litres per person per day for 3 days, for drinking. More for babies, pets and medical devices.
- Seven Oceans Emergency Drinking Water 0.5l (5-year shelf life) · EVAQ8 · £3.94 (price on 1 November 2026) Shop
Torch or head torch, plus spare batteries
Look for: Runs on the same AA or AAA batteries as your other kit, so one spare pack covers everything. A head torch leaves both hands free.
- Alpkit Ionic 350 Lumen Head Torch · Alpkit · £15.99 (price on 1 November 2026) Shop
- Lifesystems Intensity 155 LED Head Torch · Lifesystems (UK brand store) · £19.99 (price on 1 November 2026) Shop
- Alpkit Kula 550 Lumen Head Torch · Alpkit · £19.99 (price on 1 November 2026) Shop
- Lifesystems Intensity 480 LED Hand Torch · Lifesystems (UK brand store) · £29.99 (price on 1 November 2026) Shop
- Dynamo Powered Wind-Up Pocket LED Torch · EVAQ8 · £3.60 (price on 1 November 2026) Shop
Frequently asked questions
What is NUKEMAP?
A web tool created in February 2012 by Alex Wellerstein, a historian of nuclear weapons. You pick a place and a weapon size and it draws circles for the effects. It is not a government tool.
Is NUKEMAP accurate?
Only roughly. Its FAQ calls the results 'back-of-the-envelope' or 'order of magnitude' estimates. It doesn't account for terrain, buildings shielding people, or weather, and says the numbers 'might be too high' or 'too low'. Its terms say not to use it for emergency planning.
What do the psi circles mean?
psi is pounds per square inch of blast pressure. On NUKEMAP, 20 psi is labelled heavy damage, 5 psi medium damage and 1 psi light damage. The higher the number, the stronger the blast and the closer to the centre.
Does the fallout plume show where fallout would really go?
No. NUKEMAP's FAQ says its fallout model is a simple scaling model that only applies to a ground burst and doesn't model real wind conditions. An air burst produces very little local fallout. Real fallout would depend on the wind on the day.
Is there an official map of UK nuclear targets?
No. The National Risk Register 2026 says the UK's nuclear attack scenario is held internally at a higher classification. Maps shared online usually trace back to government papers from the 1970s, which Full Fact says don't reliably reflect today.
What should I do instead of checking the simulator?
Know your shelter room (the middle of the building, away from outside walls), keep 3 days of water and food, and keep a battery or wind-up radio. If a warning comes: go in, stay in, tune in.
Sources
We opened each page on the date shown. Official advice changes: if a source says something different now, follow the source.
- NUKEMAP by Alex Wellerstein: FAQ (method notes, limitations and terms of use) (read 1 November 2026)
- NUKEMAP by Alex Wellerstein: the tool (effect ring labels) (read 1 November 2026)
- Ready.gov (FEMA): Nuclear explosion (last updated 1 July 2025) (read 1 November 2026)
- UKHSA (GOV.UK): What to do in a radiation emergency (updated 10 September 2024) (read 1 November 2026)
- GOV.UK Be Ready: hazardous substance and radiation exposure (read 1 November 2026)
- Full Fact: the map of UK nuclear targets is from the 1970s (2 March 2022) (read 1 November 2026)
- Cabinet Office: National Risk Register 2026 (PDF, published July 2026), page 222 footnote on the nuclear attack scenario (read 1 November 2026)
Related guides
- Radiation emergency in the UK: what official advice says (go in, stay in, tune in)
- Worried about war? How UK households can prepare — calmly
- UK Emergency Alerts: a calm guide
We're an independent UK site, not the government. We check guides against official sources and link to them. In an emergency call 999.
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