Car Crash Calculator

This car crash calculator estimates the forces at work when a vehicle hits something and stops abruptly. When a car crashes it goes from its travelling speed to a standstill over a short distance, the crumple of the bodywork and the barrier, and the shorter that distance the harder the stop. You enter the mass of the vehicle, the speed it was travelling and the distance over which it comes to rest, and the calculator works out the average deceleration, then the average force from mass times that deceleration. It reports the force in kilonewtons, the peak deceleration expressed as a multiple of gravity, the impact speed converted to metres per second, and the kinetic energy that has to be absorbed in the collision. The physics is the standard work-energy and constant-deceleration model taught in first-year mechanics, which treats the stop as steady over the crumple distance to give a clear average rather than the jagged real-world peak. It helps explain why crumple zones, longer stopping distances and lower speeds make crashes so much more survivable, since the force falls as the stopping distance grows and rises steeply with speed. Use it for study, road-safety demonstrations or curiosity. It is a simplified estimate of average forces, not a substitute for crash engineering or accident reconstruction, which model the changing force through the impact in far more detail.

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This is the average force over the crumple distance using a constant-deceleration model. Real crashes have a changing force that peaks higher. Estimate for education only.