What formula is used?

The calculator uses c = λν (speed of light = wavelength × frequency) and E = hν (photon energy = Planck's constant × frequency). In a medium with refractive index n, the phase velocity is v = c/n, so λ = v/f.

What refractive indices are used?

Vacuum: n = 1 (exact). Air: n = 1.0003 (standard atmosphere at 589 nm). Water: n = 1.333 (sodium D line). Glass: n = 1.5 (typical borosilicate). These are representative values; real materials are dispersive.

What is the visible spectrum range?

Visible light spans roughly 380 nm to 780 nm in vacuum. The calculator further subdivides this range into approximate color bands: violet-deep (380–420 nm), violet (420–470 nm), blue (470–530 nm), green (530–580 nm), yellow (580–620 nm), orange (620–700 nm), and red (700–780 nm).

How accurate are the constants used?

The speed of light is the exact SI-defined value c = 299,792,458 m/s. Planck's constant is the exact SI-defined value h = 6.62607015 × 10⁻³⁴ J·s. The elementary charge used for eV conversion is e = 1.602176634 × 10⁻¹⁹ C (exact).

Does the medium affect photon energy?

No. Photon energy E = hν depends only on frequency, which is invariant across media. When light enters a denser medium, its wavelength shortens but its frequency — and therefore its energy — stays the same. The calculator reflects this correctly.

Wavelength & Frequency Calculator

Name: Wavelength & Frequency Calculator
Availability: InStock
Author: Nham Vu

Enter a wavelength, frequency, or photon energy — plus the medium — to instantly compute the other two values and identify the EM spectrum band.

EM Wave Input

Input Mode

Value

Medium

Enter a value on the left and press Calculate

Wavelength, frequency, and photon energy will appear here

Copied!

Summary

Enter a wavelength, frequency, or photon energy — plus the medium — to instantly compute the other two values and identify the EM spectrum band.

How it works

Select what you want to enter: Wavelength, Frequency, or Energy.
Type a value in the input field and choose your unit.
Select the medium (Vacuum, Air, Water, or Glass) from the dropdown.
Click Calculate — the other two quantities and the spectrum band appear instantly.
Use the copy buttons to copy any result to the clipboard.
Click Reset to clear all fields and start over.

Use cases

Physics and optics students verifying c = λν relationships.
Engineers calculating photon energy for laser or LED design.
Educators demonstrating electromagnetic spectrum concepts interactively.
Researchers converting spectroscopy readings between wavelength and frequency.
Amateur astronomers identifying the EM band of a measured signal.

Frequently Asked Questions

Last updated: 2026-06-09 · Reviewed by Nham Vu