E = mc² Calculator (Mass–Energy Equivalence)
E = mc² calculator: energy equivalent of a mass (or the mass of an energy) in joules, kWh and metric tons of TNT.
E = m · c²
How to use this calculator
- Choose the quantity you want under “Solve for”.
- Type the known values and pick their units: any combination works.
- The result updates as you type. Open “Show the steps” to see the substitution.
Einstein’s mass–energy equivalence: c² ≈ 9 × 10¹⁶ m²/s², so tiny masses hold enormous energy.
Formula
E = m · c²
| Symbol | Quantity | Units |
|---|---|---|
| m | Mass | kg, g, mg, µg, t, lb, oz, st, US ton, ct, Da |
| E | Energy | J, kJ, MJ, cal, kcal, Wh, kWh, eV, BTU, erg, ft·lbf |
Constants used: c = 299,792,458 m/s
Worked example
Given: m = 1 g
E = m c²
Result: E = 24 965 400 kWh
Energy for different values of Mass
| m · Mass | E · Energy |
|---|---|
| 0.5 g | 12 483 000 kWh |
| 0.75 g | 18 724 000 kWh |
| 0.9 g | 22 469 000 kWh |
| 1 g | 24 965 000 kWh |
| 1.1 g | 27 462 000 kWh |
| 1.25 g | 31 207 000 kWh |
| 1.5 g | 37 448 000 kWh |
| 2 g | 49 931 000 kWh |
Other values as in the worked example.
Frequently asked questions
Energy in 1 gram of mass?
8.99 × 10¹³ J ≈ 25 GWh ≈ 21.5 kilotons of TNT.
Related calculators
- Escape Velocity Calculator
- Buoyancy Calculator (Archimedes’ Principle)
- Friction Force Calculator
- Thin Lens Equation Calculator (Focal Length)
- Time Dilation Calculator (Special Relativity)
- Decibel Calculator (Add dB & Distance)
- Thermal Expansion Calculator (Linear)
- Speed, Distance & Time Calculator
Last updated: · Report an error