Impact Energy Calculator — Kinetic Energy at Impact
Find the energy an object carries at the moment of impact — enter mass and either the impact velocity or the height it was dropped from. Add a stopping distance to get the average impact force.
kg
Input mode
m/s
m
Kinetic energy at the moment of impact: ½mv²
- 1
Velocity squared
5² = 25 - 2
Kinetic energy at impact
½ × 10 × 25 = 125
How does this calculator work?
Impact energy = ½mv². For free fall from rest at height h, use v = √(2gh), so E = mgh. Divide energy by stopping distance d to get average impact force F = E/d. Energy grows with the square of speed — doubling velocity quadruples the impact energy.
Formula
How this is calculated
Impact energy is the kinetic energy the object has at the instant of contact: E = ½mv². If the object is dropped from rest at height h, gravity accelerates it to v = √(2gh), giving E = mgh. This is the gravitational potential energy fully converted to kinetic energy — a good approximation for compact, dense objects at everyday heights where air resistance is negligible.
Once the impact energy is known, the average impact force can be estimated as F = E / d_stop, where d_stop is the distance over which the object decelerates to rest. A short stopping distance (hard surface) produces a large force; a longer stopping distance (padding, crumple zone) reduces peak force from the same energy — the mechanical basis for safety equipment design.
The parabolic curve shows how kinetic energy scales with v². Doubling the speed quadruples the energy, which is why higher-speed collisions are disproportionately destructive. This calculator assumes a rigid point mass, ignores rotational energy and air resistance, and uses standard gravity (g = 9.80665 m/s²).
Frequently asked questions
Energy (joules) is determined by mass and velocity alone. Force (newtons) also depends on the stopping distance: the shorter the stopping distance, the higher the force needed to dissipate the same energy. A hard surface and a padded surface absorb the same energy but generate very different peak forces.
KE = ½mv² — squaring the velocity before multiplying means doubling speed quadruples energy. This is why vehicle crash standards focus heavily on speed: going from 50 km/h to 100 km/h multiplies the crash energy by four, not two.
No. The free-fall formula v = √(2gh) assumes negligible air resistance. For dense, compact objects at typical heights (a few metres) the error is small. For large, light objects or very long falls, actual impact velocity is lower due to terminal velocity limiting the speed.
Also known as
TG we-Calculate Editorial Team. (2026). Impact Energy Calculator — Kinetic Energy at Impact [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/impact-energy-calculator
TG we-Calculate Editorial Team. "Impact Energy Calculator — Kinetic Energy at Impact." TG we-Calculate. 2026. https://we-calculate.com/calculator/impact-energy-calculator.
TG we-Calculate Editorial Team, "Impact Energy Calculator — Kinetic Energy at Impact," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/impact-energy-calculator
@misc{wecalculate_impact_energy_calculator, title = {Impact Energy Calculator — Kinetic Energy at Impact}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/impact-energy-calculator}}, year = {2026}, note = {TG we-Calculate} }
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