Energy Conversion Calculator

Kilocalories (kcal) usually measure food energy. One calorie is the amount of thermal energy necessary to raise the water temperature by one degree (in the temperature of 14.5 degrees Celsius). Knowing this, you can compute the equivalent value of kilocalories expressed in joules, for example, with our specific heat calculator. The result is:

1 kcal = 4184 J,

and conversely:

1 J ≈ 0.000239 kcal.

Kilowatt-hours (kWh) are used in everyday electricity. It corresponds to the amount of energy consumed by a device within 1 hour with the power of 1000 watts (one kilowatt). Therefore, we can write:

And conversely:

In physics and chemistry, we often need to use very small energies to describe phenomena on the atomic scale. For that purpose, we can use a convenient unit called electronvolt (eV). One electronvolt is the energy obtained (or lost) by an electron that has traveled in an electric field with a potential difference of 1 volt. This energy equals:

And conversely:

In the above equation, e≈1.60217×10−19 Ce≈1.60217×10−19 C is the elementary charge of an electron. Be sure to check our acceleration in the electric field calculator, where you can estimate the acceleration of any charged particle in the electric field.

A ton of TNT is the energy unit which is the basic parameter of nuclear weapons, but it is also used to determine the strength of other events, such as meteorite impacts. One gram of TNT releases from 4100 to 4600 joules of energy from the explosion; it is conventionally assumed that it is exactly 4184 J. Therefore:

A therm is a unit of heat energy that is equivalent to burning 100 cubic feet (or 2.83 cubic meters) of natural gas. Therms are usually used by natural gas companies to calculate the actual energy use. This energy unit is useful for them because it depends only on the composition of the gas (and not on pressure or temperature). The conversion to joules is shown below:

You probably heard about the famous E = mc2 equation. Albert Einstein proposed that every mass in the world is just energy waiting to be set free. Although it is not achievable yet, we can use this formula to express the energy in the units of weight. The 1 J1 J of energy "weights":

where c≈2.998×108 m/sc≈2.998×108 m/s is the light speed.

This unit of energy is, for example, used to describe the annihilation process where an electron (with the mass me​=9.109×10−31 kgme​=9.109×10−31 kg) collides with a positron (particle with the same mass but opposite charge) and creates two photons with the energy 1.022 MeV1.022 MeV in total.

You can check it with our energy conversion calculator! Just remember that electron and positron will have the mass of 2 me​2 me​ in total.

In the classical kinetic theory of gases, the average kinetic energy per one particle is proportional to the product kB​×TkB​×T, where TT is the temperature and kB​≈1.3806×10−23 J/KkB​≈1.3806×10−23 J/K is the Boltzmann constant. Therefore, we can say that 1 J1 J of energy has the temperature of:

We sometimes use this unit of energy in physics or chemistry. For example, when we want to describe the magnitude of thermal vibrations in the crystal lattice of the material. If we say that the energy of vibrating atoms is 200 K200 K, it means that their vibrational energy is 17.235 meV17.235 meV (check it with our energy converter).

One of the central parts of the theory of quantum mechanics is matter waves. Every moving particle with specific kinetic energy behaves like a wave and can be described as having a specific wavelength. Check our De Broglie wavelength calculator to learn more about it.

In spectroscopy (the study of the interaction between matter and waves), measuring the energy of particles or light in units of reciprocal centimeters (cm⁻¹) is common. The formula for appropriate conversion is provided by Planck's equation:

where h=6.6261×10−34 m2⋅kg/sh=6.6261×10−34 m2⋅kg/s is the Planck constant, c≈2.998×108 m/sc≈2.998×108 m/s is the light speed and λλ is the wavelength. If we write down the above equation in a different form, we can say that 1 J1 J of energy will have:

You can check with our energy conversion calculator that a reciprocal centimeter describes rather low energies. For example, 50 meV=403.28 cm−150 meV=403.28 cm−1.