Photon Energy Calculator
Enter a wavelength to calculate photon energy in joules, electronvolts, and kilojoules per mole. This is an educational calculator, not laboratory or professional advice.
A QUICK WALKTHROUGH
How to use this tool
- Enter a wavelength from 1 pm to 1,000,000 nm.
- Choose nanometres, micrometres, or metres.
- Review energy per photon and per mole; the constants and equations are shown below.
Equations and constants
E = hc/λ. h = 6.62607015 × 10⁻³⁴ J·s, c = 299,792,458 m/s, e = 1.602176634 × 10⁻¹⁹ C, and Nₐ = 6.02214076 × 10²³ mol⁻¹. These are exact SI values.
Input boundary
The wavelength must be finite and between 1 pm and 1,000,000 nm after conversion to metres. Results are rounded for display; the calculation runs locally in your browser.
Educational scope
This page illustrates a monochromatic-photon relationship. It does not identify materials, prescribe exposure, or provide experimental, medical, or professional advice.
GOOD TO KNOW
Common questions
Which equation is used?
The calculator uses E = hc/λ, with wavelength converted to metres.
Why are there three energy units?
J is per photon, eV is a convenient particle-energy unit, and kJ/mol scales the same energy by Avogadro constant.
Are the constants adjustable?
No. The displayed SI constants are fixed exact values for this educational calculation.