Wavelength Calculator

Wavelength Calculator turns the wave equation into a fast, friendly tool. Type a frequency and read its wavelength, or type a wavelength and read its frequency — instantly, and completely offline. Nothing you enter ever leaves your phone.

THE PHYSICS
Every wave links speed, frequency and wavelength through one simple relationship:

v = f x lambda

So the wavelength is lambda = v / f and the frequency is f = v / lambda. The propagation speed v is set by the medium. Light travels at the speed of light c = 299,792,458 m/s in a vacuum, while sound moves at about 343 m/s in air. You can also enter any custom wave speed.

WHAT YOU CAN DO
- Frequency to wavelength: enter a value in Hz, kHz, MHz or GHz, choose a medium, and see the wavelength in the most natural unit (km, m, cm, mm, micrometres or nm)
- Wavelength to frequency: enter a length in m, cm, mm or nm and recover the frequency, plus the wave period T = 1 / f
- See the photon energy E = h x f for electromagnetic waves, using the Planck constant 6.626 x 10^-34 J*s
- Identify the electromagnetic band — radio, microwave, infrared, visible, ultraviolet, X-ray or gamma — for any light wavelength
- Learn the wave equation and explore a clear electromagnetic-spectrum reference table

WORKED EXAMPLE
A 100 MHz signal travelling at the speed of light has a wavelength of c / f = 299,792,458 / 100,000,000, which is about 2.998 m — right in the FM radio band. Switch the medium to sound and the same maths gives the wavelength of a 100 MHz acoustic wave instead.

BUILT FOR CLARITY
A clean Spectrum design puts the headline result first, with supporting figures right beside it. Light and dark themes, a tiny download, no clutter and no account required.

AN EDUCATIONAL TOOL
This app uses rounded physical constants and assumes a single, non-dispersive medium, so its results are approximate and intended for learning, study and quick checks. For engineering or safety-critical work, always confirm figures with an authoritative reference. This app is for general information and education only.

PRIVACY
The app collects no personal data and works fully offline. Ads are served by Google AdMob, which may use an advertising identifier as described in Google's policies.

Download Wavelength Calculator and move between frequency and wavelength the moment you need to.