About the Mass Energy Calculator
What is the Mass Energy Calculator?
Einstein's E = mc² shows that mass and energy are equivalent. Because the speed of light is so large, a tiny mass holds an enormous amount of energy.
Enter a mass in kilograms, grams, milligrams or atomic mass units to see the equivalent energy in several units.
How to use the Mass Energy Calculator
- Mass (sample: 1)
- Mass Unit (sample: Grams)
- Press Convert Mass to Energy (results also refresh as you type). The result card shows the Energy (E = mc²), along with In kilowatt-hours, In tonnes of TNT, In electronvolts and Energy in megajoules.
Formula used
E = m × c²
- c = 299,792,458 m/s
- 1 tonne of TNT = 4.184 × 10⁹ J
Nuclear reactions convert only a small fraction of mass – about 0.1% in fission.
Worked example
These are the sample values already filled in the calculator above, and the result it returns for them:
| Input | Sample value |
|---|---|
| Mass | 1 |
| Mass Unit | Grams |
| Result | Value |
|---|---|
| Energy (E = mc²) | 8.988 × 10¹³ J |
| In kilowatt-hours | 2,49,65,421.6316 kWh |
| In tonnes of TNT | 21,480.7643 t |
| In electronvolts | 5.61 × 10³² eV |
| Energy in megajoules | 8,98,75,517.87 MJ |
Tips for using the Mass Energy Calculator
- 1 u of mass equals about 931.5 MeV, a handy figure in nuclear physics.
- The Sun converts about 4 million tonnes of mass into energy every second.