Mass-Energy Equivalence Calculator

Calculate the energy equivalent of mass using Einstein's famous equation

E = mc²

Mass

Speed of Light (c)

m/s

Standard value: 299,792,458 m/s

Energy Unit

Real-time calculation

Result

0 J

Conversion Factors

1 kg 8.987551787 × 10¹⁶ J
1 g 8.987551787 × 10¹³ J
1 eV 1.602176634 × 10⁻¹⁹ J

About Mass-Energy Equivalence

Einstein's Famous Equation

The mass-energy equivalence formula E = mc² states that the energy (E) of a system at rest is equal to its mass (m) multiplied by the speed of light (c) squared.

This equation shows that mass and energy are interchangeable and fundamentally related.

Significance

This principle is fundamental to physics and has many applications:

Nuclear reactions (both fission and fusion)
Particle physics and antimatter
Cosmology and the Big Bang
Understanding stellar energy production

Practical Examples

Nuclear Reactions

In nuclear fission, a small amount of mass is converted to a large amount of energy:

1 kg of uranium-235 in fission releases about 8.2 × 10¹³ J
This is equivalent to about 20,000 tons of TNT

Solar Energy

The Sun converts mass to energy through nuclear fusion:

About 4 million tons of mass converted to energy every second
This powers the Sun's radiation output

Settings

Calculator Preferences

Decimal Places

Use scientific notation for large numbers

Show tooltips

Help

Enter a mass value in the input field
Select the appropriate mass unit
The speed of light is pre-filled but can be modified
Select your desired energy output unit
Click "Calculate" or let real-time calculation do it for you
View the result in the output box

The result shows how much energy would be released if the given mass were completely converted to energy.

In practical situations, only a small fraction of mass is typically converted to energy (except in matter-antimatter annihilation).

For example, nuclear reactions convert about 0.1% of mass to energy.

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