Wavelength & Frequency Calculator
Enter the wave's speed and either its frequency or wavelength to find the other.
Defaults to the speed of light (299,792,458 m/s) for electromagnetic waves — change it for sound (~343 m/s in air) or other wave types.
How the wave equation works
Every wave obeys the relationship v = f × λ, where v is the wave's speed, f is its frequency (cycles per second, in Hz), and λ (lambda) is its wavelength (the distance between repeating points, in meters).
This single equation applies to any kind of wave — light, radio waves, sound, or water waves — as long as you use the correct speed for that wave type: about 299,792,458 m/s for light in a vacuum, or about 343 m/s for sound in air at room temperature.
Frequently asked questions
Why does a higher frequency mean a shorter wavelength?
Since v = f × λ and the speed is fixed for a given medium, frequency and wavelength are inversely related — if frequency goes up, wavelength must go down to keep their product (the speed) constant.
What speed should I use for sound instead of light?
Sound travels at roughly 343 m/s in air at room temperature (20°C) — slower in less dense media, faster in denser ones like water (~1,480 m/s) or steel.
What are the units involved?
Frequency is measured in hertz (Hz, cycles per second), wavelength in meters, and speed in meters per second — consistent units ensure the equation works out correctly.