Calculadora de Energia de Einstein (E=mc²)
- Created by
- Renato Passos, Eng. de Software
- Reviewed by
- Renato Passos, Eng. de Software
Last updated: Apr 18, 2026
Formula
E = m·c²
About this calculator
The Einstein Energy Calculator (E=mc²) is an online tool that applies the famous equation of special relativity to convert mass into energy. The formula E = m·c² shows that energy (E) equals mass (m) times the square of the speed of light in vacuum (c). Since c is approximately 3×10⁸ m/s, a small mass can release a huge amount of energy. This calculator allows you to input mass in kilograms and obtain the equivalent energy in joules.
Use this calculator to understand the enormous energy contained in matter. For example, 1 kg of mass corresponds to about 9×10¹⁶ J, enough energy to power a city for years. Practical applications include understanding nuclear energy (fission and fusion) and energy production in stars. Students and physics enthusiasts can explore the mass-energy relationship concretely.
Important caveats: the equation E=mc² is valid only for objects at rest (rest mass). For moving objects, total energy includes kinetic energy. Also, complete conversion of mass into energy only occurs in processes like matter-antimatter annihilation. In nuclear reactions, only a fraction of mass is converted. Use the calculator with these limitations to avoid misinterpretations.
Frequently asked questions
What does E=mc² mean?
It means mass and energy are equivalent. The energy contained in a mass m is equal to m times the square of the speed of light.
What mass unit should I use?
Use kilograms (kg). The energy will be calculated in joules (J).
Does the calculator work for any mass?
Yes, for any mass at rest. For very small masses, the result may be very small but still valid.
Can I use this calculator for nuclear reactions?
Yes, but remember that in nuclear reactions only a fraction of mass is converted into energy. The calculator gives the maximum theoretical energy if all mass were converted.
What is the speed of light used?
We use c = 299,792,458 m/s (exact value). The calculator rounds to 3×10⁸ m/s for simplicity.