E = mc^2 Calculator

Calculate energy from mass using E = mc^2 with unit conversions.

E = mc^2 Calculator

Convert mass to energy using Einstein's equation with flexible units.

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E = mc^2 Calculator: Mass to Energy

The E = mc^2 Calculator converts mass to energy using Einstein's mass–energy equivalence. Enter mass in kilograms, grams, or pounds and choose Joules, kJ, MJ, or GJ for the result. Pair it with the Potential Energy Calculator to compare stored energy from gravity with relativistic mass energy.

How to Use

  1. Enter mass: Provide the mass value in kg, g, or lb.
  2. Select units: Choose your input mass unit and desired energy unit.
  3. Calculate: Click Calculate to apply E = mc^2 instantly.
  4. Review steps: See the detailed calculation with constants and conversions.
  5. Reset: Clear inputs to run another scenario.

Core Formula

E = m \times c^2

Energy equals mass multiplied by the speed of light squared (c = 299,792,458 m/s).

  • Mass in kilograms is standard SI input
  • Energy output available in J, kJ, MJ, or GJ
  • Speed of light constant: 299,792,458 m/s

Applications

  • Estimate theoretical energy from matter-antimatter conversion
  • Benchmark energy content versus chemical or potential energy
  • Educational demonstrations of relativity basics
  • Quick unit conversions for engineering studies
  • Physics coursework and research notes

What value of c is used?

The calculator uses the speed of light in vacuum: 299,792,458 meters per second.

Can I enter negative mass?

No. Mass must be zero or positive for a valid physical result.

Which energy units are supported?

Joules, kilojoules, megajoules, and gigajoules are available for output.

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