⚛️ Relativistic Kinetic Energy Calculator
Calculate the relativistic kinetic energy of an object at any speed, including speeds approaching that of light.
1
kg
2
×c
What relativistic kinetic energy is
At speeds approaching the speed of light, the classical (Newtonian) kinetic energy formula becomes inaccurate. Special relativity provides the correct formula that remains valid at any speed below light speed.
The formula
Relativistic kinetic energy KE = (γ − 1)mc², where γ = 1/√(1 − v²/c²) is the Lorentz factor, m is the rest mass, and c is the speed of light. At low speeds this reduces closely to the familiar ½mv², but it diverges toward infinity as speed approaches c.
This calculator is intended for general physics education; it uses the standard special relativity kinetic energy formula.
Last reviewed August 2026