Wavelength & Frequency Calculator
Convert between wavelength and frequency for any wave.
What is the Wavelength & Frequency Calculator?
A wavelength and frequency calculator converts between a wave's wavelength and its frequency, using the fundamental relationship that wave speed equals frequency multiplied by wavelength (v = fλ). It works by rearranging that formula depending on which value you know: if you enter frequency, wavelength is calculated as speed ÷ frequency; if you enter wavelength, frequency is calculated as speed ÷ wavelength. For light and other electromagnetic waves, the speed used is the speed of light in a vacuum (299,792,458 m/s); for sound, wave speed varies by medium and temperature, with 343 m/s being a typical value for air at room temperature. To calculate it manually, use λ = v ÷ f or f = v ÷ λ with the appropriate wave speed for your situation.
How it works
Every wave follows the same fundamental relationship: wave speed equals frequency multiplied by wavelength. Rearranging this formula lets you calculate wavelength from frequency (or vice versa) provided you know the wave's speed — for light and other electromagnetic waves travelling through a vacuum, that speed is the universal constant known as the speed of light.
UK context
Sound waves and light waves behave very differently here: light's speed in a vacuum is a fixed universal constant, while sound's speed depends entirely on the medium it's travelling through (and, for a given medium like air, on temperature) — there's no single "speed of sound" the way there's a fixed speed of light, which is why this calculator lets you specify a wave speed for sound.
Tips
- For light and other electromagnetic waves, always use the vacuum speed of light unless you're specifically accounting for the wave slowing down in a different medium (like light travelling through glass or water).
- Sound speed increases with temperature in air — 343 m/s is a commonly used value for dry air at roughly room temperature, but it changes with conditions.
Frequently asked questions
What is the relationship between wavelength and frequency?
Wave speed = frequency × wavelength. For a fixed wave speed, wavelength and frequency are inversely related — higher frequency means shorter wavelength, and vice versa.
Does the speed of sound change?
Yes, significantly — unlike the speed of light in a vacuum (a fixed constant), the speed of sound depends on the medium it travels through and, within a given medium like air, on temperature and other conditions.
A quick note
Light/EM waves use the speed of light in a vacuum (a fixed constant); sound speed varies by medium and temperature, so the value used is illustrative unless you enter your own measured figure.