Wavelength Calculator
Wavelength (m)0.779545
Frequency (Hz)440.0000
Velocity (m/s)343.0000
The Wavelength Calculator relates the three quantities of a travelling wave — wavelength, frequency, and wave speed — through the relation v = f × λ. Pick which of the three you want to solve for, supply the other two, and the calculator returns the missing value. It works for any wave, whether you use the speed of light for electromagnetic waves or the speed of sound for acoustics.
Formula
v = f × λ (so λ = v / f and f = v / λ)
- v
- Wave speed (e.g. ~3×10⁸ m/s for light, ~343 m/s for sound in air)
- f
- Frequency in hertz (cycles per second)
- λ
- Wavelength (distance between successive crests)
How it works
- Choose what to solve for: wavelength, frequency, or velocity (wave speed).
- Enter the two known quantities. To solve for wavelength the calculator divides velocity by frequency; to solve for frequency it divides velocity by wavelength; to solve for velocity it multiplies wavelength by frequency.
- Use consistent units (e.g. metres, hertz, metres per second). Solving for wavelength or frequency requires the divisor to be non-zero.
Worked examples
Find the wavelength of a 100 MHz FM radio wave travelling at the speed of light.
- Use λ = v / f with v = 3×10⁸ m/s and f = 100,000,000 Hz.
- λ = 300,000,000 ÷ 100,000,000 = 3 m.
The wavelength is 3 metres.
Find the frequency of a 2 m sound wave in air (v ≈ 343 m/s).
- Use f = v / λ with v = 343 m/s and λ = 2 m.
- f = 343 ÷ 2 = 171.5 Hz.
The frequency is 171.5 Hz.
Frequently asked questions
- What is the relationship between wavelength and frequency?
- They are inversely related at a fixed wave speed: wavelength equals speed divided by frequency. As frequency rises, wavelength shortens, and their product always equals the wave speed.
- What wave speed should I use?
- For electromagnetic waves in a vacuum use the speed of light, about 3×10⁸ m/s. For sound in air at room temperature use roughly 343 m/s. Use the medium-appropriate speed for other cases.
- What units does the calculator expect?
- It performs pure arithmetic on the numbers you enter, so keep units consistent — for example metres per second, hertz, and metres — and the result will be in the matching unit.
- Why can frequency or wavelength not be zero when solving?
- Solving for wavelength divides by frequency, and solving for frequency divides by wavelength, so the divisor must be non-zero. A zero would mean a wave that never oscillates or has no length.