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Find wavelength, frequency, or wave speed with v = fλ, for sound, light and radio (c = fλ), and photon energy from wavelength with E = hc/λ.
Also covers: v = fλ calculator · Frequency to wavelength · Wavelength to frequency · Photon energy calculator
v = f × λ
The defaults are a 440 Hz tone (concert A) in air at 20 °C, where sound travels at about 343 m/s.
Wavelength (λ)
0.77954545 m
In other units
Working
Choose any wave (v = fλ), light and radio (c = fλ), or photon energy (E = hc/λ) and which variable to solve for; the form asks only for the others.
Each input has its own unit picker, so you can mix km, cm, µC or MHz without converting first.
You get the result in your chosen unit and every other unit, plus the rearranged equation with your numbers in SI units.
Divide the wave speed by the frequency: λ = v / f. A 440 Hz sound in air (343 m/s) has a wavelength of about 0.78 m; 100 MHz FM radio has a wavelength of about 3 m.
About 343 m/s for sound in air at 20 °C, around 1,480 m/s in water, and 299,792,458 m/s for light and radio in a vacuum. Use the Light and radio formula to have c filled in for you.
E = hc / λ, so shorter wavelengths carry more energy. Visible light spans about 380–750 nm, or roughly 3.3 to 1.65 eV per photon.
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