# Photon Energy Calculator

URL: https://speedycalculator.com/calculators/physics/photon-energy/
Last updated: 2026-10-25

> The photon energy calculator finds the energy of a photon from its wavelength using E = hc ÷ λ, in joules and electronvolts, and gives its frequency.

## Inputs

- Wavelength (nm, µm, m)

## Results

- Photon energy
- Energy in electronvolts
- Frequency

## Formula

```
E = h c ÷ λ
```

## Explanation

Light comes in packets called photons. Shorter wavelengths, such as ultraviolet, carry more energy per photon.

### How to use the Photon Energy Calculator

- **Wavelength**
- Want to work backwards? Type a value into **Photon energy** and **Wavelength** is calculated for you.

Results update as you type, and every field accepts the units shown in its menu.

### How it works

Multiply Planck’s constant by the speed of light and divide by the wavelength.

### What each result means

- **Photon energy** = 6.62607015[Photon energy]-34 × 299792458 ÷ [Wavelength]
- **Energy in electronvolts** = [Photon energy] ÷ 1.602176634[Photon energy]-19
- **Frequency** = 299792458 ÷ [Wavelength]

### Example values

How the main result changes when **Wavelength** changes and everything else stays at the example values above:

Wavelength (nm)Photon energy (J)2757.2234e-19412.54.8156e-195503.6117e-19687.52.8894e-198252.4078e-191,1001.8059e-19

## Worked example

Inputs — Wavelength: 550 nm.

Results — **Photon energy = 3.6117e-19 J**; Energy in electronvolts = 2.2543 eV; Frequency = 545,077,196,363,636.3 Hz.

## FAQ

**What is an electronvolt?**
The energy an electron gains crossing 1 volt: 1.602 × 10⁻¹⁹ J.

**Why can UV cause sunburn but radio waves cannot?**
UV photons carry enough energy to damage molecules.

**What formula does the Photon Energy Calculator use?**
E = h c ÷ λ.

**Can I work backwards from the result?**
Yes. Type the result you want into Photon energy and the calculator finds the matching wavelength.


## Sources

- [NIST – Fundamental physical constants](https://physics.nist.gov/cuu/Constants/)