Mass-Energy Equivalence (E = mc²)
Also known as E = mc² · einstein's equation
Enter your known values, leave one input blank, and solves for the missing one. Try different units for next level excitement!
Constant used — built into this formula, no need to enter
Speed of light in vacuum · exactLearning zone
The most famous equation in physics says mass is frozen energy, with an exchange rate of c² ≈ 9 × 10¹⁶ J/kg: one gram fully converted equals 90 TJ, about the energy of the Hiroshima bomb — or three days of output from a large power station. Nothing we build converts mass completely; fission liberates about 0.1% of the fuel's mass, fusion in the Sun about 0.7%, turning 4 billion kilograms of solar mass into light every second. The equation also runs in reverse: particle colliders routinely condense kinetic energy into brand-new particles.
Mass-Energy Equivalence (E = mc²)
Where
- = Rest energy
- = Mass
Missing one of these? Work it out first, then come back
- Rest energy — Kinetic Energy, Photon Energy (E = hf)
- Mass — Newton's Second Law, Kinetic Energy