Wavelength, Speed and Frequency Calculator

The wave equation

The speed of a wave equals its frequency times its wavelength: v = f × λ. Frequency (f) is the number of oscillations per second, measured in hertz. Wavelength (λ) is the distance between two successive crests. The relation holds for sound, light, radio and water waves alike.

Three ways to use it

• Wavelength: λ = v / f
• Frequency: f = v / λ
• Speed: v = f × λ
• Period: T = 1 / f (the time for one oscillation)

In a given medium the speed is fixed, so a higher frequency means a shorter wavelength.

Example: sound

Sound travels through air at about 343 m/s. The note A at 440 Hz has a wavelength of 343 / 440 = 0.78 m. Sounds the human ear can hear, from 20 Hz to 20 kHz, have wavelengths from about 17 m down to 1.7 cm.

Example: radio

An FM station broadcasting at 100 MHz has a wavelength of 299 792 458 / 100 000 000 = 3.00 m.

Limits

Speed depends on the medium and you have to enter it. The speed of sound changes with air temperature and the speed of light with the refractive index of the medium. When a wave enters another medium its frequency stays the same and its wavelength changes with the new speed.