Given below energy of light with wavelength formula to calculate joules, kilojoules, eV, kcal. Here planck's equation is used in finding the energy by using the wavelength of the light. Photon energy is used for representing the unit of energy. Wavelength to Joules formula is defined as (6.626xc)/w. Multiply the planck's constant value, 6.626 with the speed of light (300000000 m/s). Then divide the obtained value by the wavelength of weight. The resultant value is the energy of light.