Mass Energy Equivalence Calculator
Enter a mass value and instantly get its equivalent energy using E=mc², displayed in joules, kilojoules, megajoules, kilowatt-hours, and electron-volts.
Enter Mass
Formula: E = mc²
c = 299,792,458 m/s | c² ≈ 8.9876 × 10¹⁶ J/kg
Energy Equivalents
Enter a mass value and click Calculate
Results will appear here in multiple energy units
Mass in kilograms:
Joules
SI base unit of energy
Kilojoules (kJ)
10³ joules
Megajoules (MJ)
10⁶ joules
Kilowatt-hours (kWh)
Common electricity billing unit (1 kWh = 3.6 MJ)
Electron-volts (eV)
Used in atomic and particle physics
Mega electron-volts (MeV)
Nuclear physics unit (1 MeV = 10⁶ eV)
Context
Summary
Enter a mass value and instantly get its equivalent energy using E=mc², displayed in joules, kilojoules, megajoules, kilowatt-hours, and electron-volts.
How it works
- Enter a mass value in the input field.
- Select the unit of mass (kilograms, grams, milligrams, pounds, or atomic mass units).
- The calculator multiplies the mass in kilograms by c² (≈ 8.9875 × 10¹⁶ J/kg).
- Results are displayed simultaneously in joules, kilojoules, megajoules, kilowatt-hours, and electron-volts.
- Use the copy button next to any result to copy that value to your clipboard.
Use cases
- Physics students verifying E=mc² homework problems.
- Understanding the energy released in nuclear reactions.
- Comparing the energy density of matter to conventional fuels.
- Teaching and demonstrating the concept of mass-energy equivalence.
- Engineering calculations involving relativistic energy.
- Exploring the implications of antimatter annihilation.
- Scientific research and reference conversions.
- Estimating the theoretical yield of nuclear devices.