Photon Energy Calculator (E = hf = hc/λ)
Photon Energy Calculator (E = hf = hc/λ)
Photon energy is the quantum of energy carried by a single photon of light, proportional to its frequency (or inversely proportional to its wavelength) via Planck's constant. Choose whether you know the frequency or the wavelength, enter the value, and this calculator computes the photon's energy in both joules and electronvolts with a full step-by-step solution.
- E = hf, where h is Planck's constant (6.626×10⁻³⁴ J·s) and f is frequency in Hz - or equivalently E = hc/λ, where c is the speed of light and λ is wavelength.
- 500 nm (green light) has a photon energy of about 3.973×10⁻¹⁹ J, or 2.48 eV - matching the well-known ~2.5 eV figure for visible light in physics and chemistry.
- Shorter wavelength means higher energy - this is why ultraviolet and X-ray photons can damage tissue and break chemical bonds, while lower-energy infrared and radio photons cannot.
How do I calculate photon energy from wavelength?
Use E = hc/λ, where h = 6.626×10⁻³⁴ J·s, c = 299,792,458 m/s, and λ is the wavelength in meters.
How do I convert photon energy from joules to electronvolts?
Divide the energy in joules by 1.602×10⁻¹⁹ J (the value of 1 eV) to get electronvolts.
Photon Energy Calculator (E = hf = hc/λ)
Photon energy is the quantum of energy carried by a single photon of light, proportional to its frequency (or inversely proportional to its wavelength) via Planck's constant. Choose whether you know the frequency or the wavelength, enter the value, and this calculator computes the photon's energy in both joules and electronvolts with a full step-by-step solution.
- E = hf, where h is Planck's constant (6.626×10⁻³⁴ J·s) and f is frequency in Hz - or equivalently E = hc/λ, where c is the speed of light and λ is wavelength.
- 500 nm (green light) has a photon energy of about 3.973×10⁻¹⁹ J, or 2.48 eV - matching the well-known ~2.5 eV figure for visible light in physics and chemistry.
- Shorter wavelength means higher energy - this is why ultraviolet and X-ray photons can damage tissue and break chemical bonds, while lower-energy infrared and radio photons cannot.
How do I calculate photon energy from wavelength?
Use E = hc/λ, where h = 6.626×10⁻³⁴ J·s, c = 299,792,458 m/s, and λ is the wavelength in meters.
How do I convert photon energy from joules to electronvolts?
Divide the energy in joules by 1.602×10⁻¹⁹ J (the value of 1 eV) to get electronvolts.