Asteroid Impact Effects Calculator
Estimate the effects of an asteroid impact, including seismic shaking, airblast, and thermal radiation, at your specified distance.
Last reviewed: June 2026Impactor Properties
Target & Your Location
Impactor Energy
Effects at Your Location
Effects Profile
This board turns the current scenario into relative bands so you can see whether shaking, airblast, heat, or the secondary hazard dominates.
Effect Zones from Impact Point
| Effect | Radius | Description |
|---|
Effect Zones Visualization
Impact Zone Map
Click anywhere on the map or select a location to visualize impact zones. Ocean locations will show tsunami effects.
What this asteroid impact calculator estimates
This asteroid impact effects calculator turns a hypothetical impactor into a first-pass effects profile at a selected distance. It estimates impactor mass, kinetic energy, atmospheric breakup or surface impact outcome, approximate crater diameter, seismic shaking, airblast overpressure and arrival time, thermal fluence, ejecta thickness, and a rough tsunami wave-height proxy when the selected target is water.
The calculator is built for education, scenario comparison, and model intuition. It is not an orbit-prediction tool and it does not know whether a real object is on an impact trajectory. For real near-Earth object monitoring, use official NASA/JPL resources such as CNEOS Sentry and CNEOS fireball data. For detailed impact effects, use purpose-built impact-effects models and expert review.
How the main inputs change the result
Impactor diameter controls both mass and the crater scaling term, so small changes can produce large energy changes. Composition changes density: comet-like ice, carbonaceous material, stony material, and iron-nickel bodies do not carry the same mass at the same diameter. Velocity enters kinetic energy as velocity squared, which means a faster object can be much more energetic even when diameter is unchanged.
Impact angle is measured from the horizontal. A 90 degree impact is vertical; a smaller value is more grazing. The calculator uses the angle in crater scaling and entry interpretation, but it does not simulate the full asymmetric ejecta pattern of an oblique impact. Your distance is the straight-line distance used for local effects at the selected unit. Target surface changes the target density and whether the page shows ocean-impact tsunami output.
Reading the output panels
Kinetic Energy is shown as TNT equivalent with a Hiroshima-reference comparison. Treat that as a scale reference, not a damage forecast. Atmospheric Entry uses a compact breakup estimate, so smaller objects may be reported as airbursts and therefore show no permanent crater. Crater Diameter uses simplified gravity-regime crater scaling for surface impacts and links to the more focused crater-diameter calculator for users who want to inspect that part of the model.
Seismic Shaking reports an earthquake-magnitude equivalent and a distance-adjusted intensity label. Impact seismic coupling is not the same as a tectonic earthquake, and local geology matters. Airblast reports a pressure estimate and arrival time, but it does not model terrain shielding, structures, glass type, urban layout, or atmospheric weather. Thermal Radiation is a line-of-sight fluence proxy; clouds, curvature, smoke, terrain, and fire-starting conditions are outside this page's model.
Ejecta is a rough blanket-thickness estimate from crater geometry and distance. It should not be read as a debris-map forecast. Tsunami Wave Height appears for ocean impacts and is intentionally labeled as approximate. It does not model seafloor bathymetry, shoreline shape, wave dispersion, tides, coastal runup, or local evacuation planning.
Worked default scenario
The default scenario uses a 100 m stony impactor at 20 km/s and a 45 degree angle, with the observer 100 km from a sedimentary-rock target. The calculator reports about 75.1 megatons TNT of kinetic energy, about 1.57 gigatonnes of impactor mass, and an airburst around 15.9 km altitude. Because the simplified entry model treats this object as fragmenting before it reaches the ground, the crater panel reports no crater. The same scenario still reports local airblast, thermal exposure, and reduced seismic coupling because the energy is released in the atmosphere.
This example is useful because it shows why energy alone is not enough. Two scenarios with similar kinetic energy can look different if one reaches the surface and the other airbursts. Diameter, density, velocity, angle, target material, and distance all shape the result.
Limits and responsible use
The calculator leaves out object shape, strength distribution, fragmentation cascades, ablation, lift, detailed atmospheric trajectory, terrain, building vulnerability, fire spread, casualty estimation, economic loss, local weather, and official response decisions. Large impacts also require climate and ejecta modeling far beyond this browser tool. Use the output to compare scenarios and learn which physical inputs matter most; do not use it to make safety, property, insurance, or public-response decisions.
Sources and further reading
Useful references for understanding the assumptions and context include the Earth Impact Effects Program from Purdue University and Imperial College London, the Imperial College Impact: Earth effects documentation, NASA's Planetary Defense Coordination Office overview, JPL CNEOS Sentry risk table, and JPL CNEOS fireball and bolide data.
Frequently Asked Questions
Quick reference
| Output | Use it for |
|---|---|
| Energy and mass | Comparing impactor scale from diameter, density, and speed. |
| Entry and crater | Seeing whether the simplified model treats the event as an airburst or surface impact. |
| Blast, thermal, seismic | Comparing local effect bands at the selected distance. |
| Ejecta and tsunami | Learning when secondary effects can dominate the scenario. |