How To Convert Electronvolt to Joule
Formula: 1 electronvolt = 1.602176634 × 10-19 joule.
Example: Convert 7.5 electronvolt to joule.
7.5 × 1.602176634 × 10-19 = 1.2016324755 × 10-18 joule.
To convert by hand, you multiply the electronvolt value by a fixed number. That number is very small because a joule is a large unit compared to an electronvolt. You will usually write the answer in scientific notation. Keep the same power of 10 and multiply only the front number first, then place the exponent back.
Quick Answer
1 Electronvolt = 1.602176634 × 10-19 Joule
- 2 electronvolt = 3.204353268 × 10-19 joule
- 10 electronvolt = 1.602176634 × 10-18 joule
- 1000 electronvolt = 1.602176634 × 10-16 joule
Conversion Formula
Recommended (SI definition): 1 eV = 1.602176634 × 10^-19 J J = eV × 1.602176634 × 10^-19 eV = J ÷ (1.602176634 × 10^-19)
This means an electronvolt is defined using the exact value of the elementary charge. If you have energy in electronvolt and want joule, you multiply by 1.602176634 × 10-19. If you have joule and want electronvolt, you divide by the same number.
- Write your value in electronvolt.
- Multiply it by 1.602176634 × 10-19.
- Keep the result in joule, usually in scientific notation.
Electronvolt
An electronvolt is a unit of energy equal to the energy gained by one electron when it moves through an electric potential difference of 1 volt. The symbol is eV.
It became common in early atomic and nuclear physics because it matches the tiny energies of particles. Today, it is widely used in physics, chemistry, and electronics for small energy scales.
- Photon energies in light and lasers
- Band gaps of semiconductors
- Ionization energies of atoms and molecules
- Electron and ion energies in plasma physics
- X-ray and gamma ray energies (often in keV or MeV)
Joule
A joule is the SI unit of energy. The symbol is J.
It is named after James Prescott Joule, who helped explain the relationship between heat and mechanical work. In modern SI, it is used everywhere for energy in physics, engineering, food, and electricity.
- Electrical energy, like watt seconds
- Mechanical work, like lifting and pushing
- Heat and thermal calculations
- Energy in batteries and power systems
- Scientific measurements and lab reports
Is this Conversion of Electronvolt To Joule Accurate?
Yes. This conversion is based on the SI definition of the elementary charge, which is fixed exactly. Since 1 eV is defined as the energy of one elementary charge moved through 1 volt, the value 1 eV = 1.602176634 × 10-19 J is exact and is the same value used in textbooks and scientific work. For more details, read our standards page at accuracy standards.
Real Life Examples
Electronvolt is common when energies are very small, like in atoms, electrons, and light. Here are realistic examples converted to joule.
- Silicon band gap (about 1.12 eV): 1.12 eV = 1.79443783008 × 10-19 J, useful in solar cell and chip design.
- Green light photon (about 2.0 eV): 2.0 eV = 3.204353268 × 10-19 J, helpful when comparing light energy to detector sensitivity.
- Blue LED photon (about 3.1 eV): 3.1 eV = 4.9667475654 × 10-19 J, used in LED and display engineering.
- Hydrogen ionization energy (13.6 eV): 13.6 eV = 2.17896022224 × 10-18 J, common in atomic physics problems.
- Low energy electron in a microscope (500 eV): 500 eV = 8.01088317 × 10-17 J, used when estimating beam interactions with a sample.
- X-ray energy (6.2 keV): 6200 eV = 9.9334951308 × 10-16 J, used in imaging, material testing, and spectroscopy.
- Gamma ray energy (1 MeV): 1,000,000 eV = 1.602176634 × 10-13 J, used in nuclear physics and radiation safety calculations.
Quick Tips
- Remember the core fact: 1 eV ≈ 1.6 × 10-19 J for fast mental math.
- To go from eV to J, multiply. To go from J to eV, divide.
- keV to J: multiply the keV value by 1.602176634 × 10-16.
- MeV to J: multiply the MeV value by 1.602176634 × 10-13.
- Use scientific notation to avoid long strings of zeros.
- Keep consistent significant digits based on your input value, even though the constant is exact.