Photon Energy Calculator

Use our photon energy calculator to calculate frequency (GHz) and photon energy (meV) from wavelength (λ) in millimeters (mm). Includes the photon energy formula, photon energy from wavelength, and how photon energy relates to frequency.

Wavelength (λ) (mm)

Results

Frequency (GHz)

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Energy (meV)

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Steps: λ(mm) → m, f = c/λ, E = h·f, then convert J → eV and eV → meV.

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Photon Energy Explained

A photon is a quantum (packet) of electromagnetic radiation. Photons carry energy that depends on frequency: higher frequency means higher photon energy.

Wavelength and frequency are linked by the speed of light, so you can calculate photon energy from wavelength as well.

This calculator takes wavelength (λ) in millimeters (mm) and returns frequency in gigahertz (GHz) and photon energy in millielectronvolts (meV).

Photon Energy Formula

Convert wavelength to meters, compute frequency, then compute energy and convert units.

Convert wavelength (mm → m) =

λ(m) = λ(mm) ÷ 1000

1 mm = 0.001 m.

Frequency from wavelength =

f(Hz) = c ÷ λ(m)

c is the speed of light (≈ 299,792,458 m/s).

Convert frequency (Hz → GHz) =

f(GHz) = f(Hz) ÷ 10^9

1 GHz = 10^9 Hz.

Photon energy =

E(J) = h × f(Hz)

h is Planck’s constant (≈ 6.62607015×10^-34 J·s).

Convert energy (J → meV) =

E(meV) = (E(J) ÷ e) × 1000

e is the elementary charge (≈ 1.602176634×10^-19 J/eV).

Direct form (from wavelength) =

E = (h × c) ÷ λ

Use consistent units. This calculator uses λ in meters internally.

= Wavelength

= Frequency

= Photon energy

= Speed of light

= Planck’s constant

Example: photon energy from wavelength

λ = 1 mm → λ = 0.001 m → f = 299,792,458 / 0.001 = 2.99792458×10^11 Hz = 299.792 GHz → E = h f = 1.986×10^-22 J → E ≈ 1.240 meV

Shorter wavelength means higher frequency and higher photon energy.

How to Calculate Photon Energy From Wavelength

1
Enter wavelength (λ) in millimeters (mm).
2
The calculator converts mm to meters and computes frequency using f = c/λ.
3
It converts frequency to GHz and computes photon energy using E = h f.
4
It converts joules to meV and shows both results.

Frequently Asked Questions

How to calculate photon energy from wavelength?

Compute frequency from wavelength (f = c/λ), then energy (E = h f). You can also use the direct form E = h c / λ with consistent units.

How does photon energy relate to frequency?

Photon energy is directly proportional to frequency: E = h f. Higher frequency means higher photon energy.

How much energy does a photon have?

It depends on wavelength or frequency. Shorter wavelengths (higher frequencies) have more energy per photon.

Is photon an energy?

A photon is a particle/quantum of electromagnetic radiation. It carries energy, but it is not “energy itself.”

What is the photon energy unit?

Photon energy is often expressed in electronvolts (eV). This calculator reports energy in millielectronvolts (meV), where 1 meV = 0.001 eV.

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