Wavelength Calculator
Work out wavelength, frequency or wave speed with the formula v = f × λ. Fill in two of the three fields and leave the third at 0, and the calculator works out the rest.
How to use the wavelength calculator
- Enter the two values you know: wave speed, frequency or wavelength.
- Leave the field you don't know at 0 — the calculator automatically works out that value.
- If you fill in all three fields, the calculator instead checks whether they're actually consistent.
The relationship between wavelength, frequency and speed
Worked example: a 440 Hz tone (concert pitch A) in air, where sound travels at 340 m/s, has a wavelength of 340 ÷ 440 = 0.77 m. A deep 40 Hz tone gives 340 ÷ 40 = 8.5 m by comparison — which is why bass requires far larger speakers than treble.
Wave speed (v) equals frequency (f) multiplied by wavelength (λ). The formula applies to all types of waves — sound waves, light waves and water waves — as long as the speed stays constant in the medium the wave travels through.
Sound in air has a speed of about 340 m/s, while light travels enormously faster, at about 3 × 10⁸ m/s in a vacuum. That's why lightning is seen long before thunder is heard, even though both occur at the same time.
Frequently asked questions
What's the relationship between wavelength and frequency?
Wavelength and frequency are inversely proportional when speed is constant: the higher the frequency, the shorter the wavelength, and vice versa. The relationship is described by the formula v = f × λ, where v (the speed) stays fixed for a given medium.
Why is the speed of sound different in air and water?
The speed of sound depends on how tightly packed the molecules in the medium are and how quickly they can transfer vibrations to each other. Water is far denser than air, so sound travels much faster in water (about 1,480 m/s) than in air (about 340 m/s).
Can I use this for light waves too?
Yes, the formula v = f × λ also applies to light, but then you need to use the speed of light (about 3 × 10⁸ m/s in a vacuum) as the wave speed instead of the speed of sound. Light's wavelengths are in turn far shorter than sound's.