Max Theoretical Efficiency of a Lamp

For a given wavelength the energy of a photon in inversely proportional to it's wavelength. For a given wavelength we can calculate the energy of photon. Then we can calculate the number of photons of that  wavelength that can be produce with 1 Joule of energy and express it in Moles as unit.

Calculator below can be used to estimate max efficiency of a color LED. For PC(phosporus converted) LED enter the wavelength of the blue pump.

Wavelength (nm) :


Energy of each photon (joules) :

A lamp running at 100% efficiency, producing only the wavelength above will have photometric efficiency of.

μmol/J :



E = h × c / λ

h is Planck's constant 6.62607015×10-34m2kg/s

c is the speed of light 299792458 m/s

λ is wavelength of light in meters

mole is 6.02214076×e+23


This calculator is designed for education use only.