Science
Frequency and wavelength
Calculate wavelength from frequency and propagation speed.
Calculators / Science / Photon energy from wavelength
Photon energy from wavelength calculator
Convert vacuum wavelength in nanometres into the energy of one photon in joules and electronvolts using Planck’s constant and light speed.
On this page
Photon energy3.97e-19J
Photon energy2.48eV
Calculator controls
How to calculate
Convert vacuum wavelength in nanometres into the energy of one photon in joules and electronvolts using Planck’s constant and light speed.
Photon energy = 6.62607015e-34*299792458/(l/1000000000) J; Photon energy = 6.62607015e-34*299792458/(l/1000000000)/1.602176634e-19 eV
Worked example
Wavelength (nm): 500.
Photon energy: 3.97e-19 J; Photon energy: 2.48 eV.
Assumptions and limits
Convert vacuum wavelength in nanometres into the energy of one photon in joules and electronvolts using Planck’s constant and light speed. Photon wavelength is in vacuum. The inverse-square model assumes an unobstructed point source without absorption; intensity has units of power per area.
Results are rounded for display; calculations use unrounded values. Read our calculation methodology.
Understanding the result
Convert vacuum wavelength in nanometres into the energy of one photon in joules and electronvolts using Planck’s constant and light speed.
When this tool is useful
Photon energy = 6.62607015e-34*299792458/(l/1000000000) J; Photon energy = 6.62607015e-34*299792458/(l/1000000000)/1.602176634e-19 eV
Understanding your inputs
| Input | What to enter |
|---|---|
| Wavelength (nm) | Enter a number of at least 1e-12 and no more than 1000000000000. |
Frequently asked questions
What assumptions does this calculation use?
Convert vacuum wavelength in nanometres into the energy of one photon in joules and electronvolts using Planck’s constant and light speed. Photon wavelength is in vacuum. The inverse-square model assumes an unobstructed point source without absorption; intensity has units of power per area.
How is the result calculated?
Photon energy = 6.62607015e-34*299792458/(l/1000000000) J; Photon energy = 6.62607015e-34*299792458/(l/1000000000)/1.602176634e-19 eV