Wavelength Frequency Energy Converter

Light and electromagnetic radiation can be described by three linked properties — wavelength, frequency, and energy — and knowing one lets you calculate the other two. Select Calculate From to choose your known value, then enter your wavelength (nm, µm, mm, cm, or m), frequency (Hz to THz), or energy (eV, J, keV, or MeV) into the Wavelength Frequency Energy Converter to get all three properties at once. Outputs include wavelength in nm, frequency in Hz, and energy in both eV and joules.

Calculate From *

nm
Hz
eV

Results

Wavelength

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Frequency

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Energy (eV)

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Energy (Joules)

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Frequently Asked Questions

How do I calculate energy from wavelength?

To calculate photon energy from wavelength, use Planck's equation: E = hc/λ, where h is Planck's constant (6.626 × 10⁻³⁴ J⋅s), c is the speed of light (3 × 10⁸ m/s), and λ is the wavelength in meters.

How do I find the energy in joules given the wavelength?

Convert the wavelength to meters, then apply E = hc/λ. For example, for 550 nm light: convert to 550 × 10⁻⁹ m, then calculate E = (6.626 × 10⁻³⁴ × 3 × 10⁸) / (550 × 10⁻⁹) = 3.61 × 10⁻¹⁹ J.

How do I convert wavelength to energy in eV?

First calculate energy in joules using E = hc/λ, then convert to electronvolts by dividing by the elementary charge (1.602 × 10⁻¹⁹ C). Alternatively, use the direct formula: E(eV) = 1240/λ(nm).

What is the relationship between frequency and wavelength?

Frequency and wavelength are inversely related by the speed of light: c = λf, where c is the speed of light, λ is wavelength, and f is frequency. Higher frequency means shorter wavelength.

What is the energy of a 100 nm photon?

A 100 nm photon has an energy of approximately 12.4 eV or 1.99 × 10⁻¹⁸ joules. This is in the ultraviolet range of the electromagnetic spectrum.

What are typical wavelength ranges for different types of electromagnetic radiation?

Visible light: 380-700 nm, UV: 10-380 nm, infrared: 700 nm-1 mm, radio waves: 1 mm-100 km, X-rays: 0.01-10 nm, gamma rays: <0.01 nm.

Why is Planck's constant important in these calculations?

Planck's constant (h = 6.626 × 10⁻³⁴ J⋅s) is fundamental to quantum mechanics and relates the energy of a photon to its frequency or wavelength. It's the proportionality constant in Planck's equation E = hf.