Wavelength Calculator

v = f x lambda, where v is wave speed, f is frequency in hertz, and lambda is wavelength. For light in vacuum, v = c = 2.998 x 10^8 m/s. For sound in air at 20 C, v is about 343 m/s. Solve for any of the three given the other two.

Visible light spans roughly 380 nm (violet) to 750 nm (red). Green light at 550 nm has a frequency of c / lambda = 2.998 x 10^8 / 5.50 x 10^-7 = 5.45 x 10^14 Hz, or 545 THz.

E = h x c / lambda, where h is Planck's constant (6.626 x 10^-34 J s). For 550 nm green light: E = 6.626e-34 x 2.998e8 / 5.50e-7 = 3.61 x 10^-19 J, or 2.25 eV. The calculator does this automatically for any EM wave.

This calculator classifies wavelengths above 1 m as radio, 1 mm to 1 m as microwave, 750 nm to 1 mm as infrared, 400 to 750 nm as visible light, 10 to 400 nm as ultraviolet, and shorter wavelengths as X-ray or gamma ray. Band boundaries vary by convention, so use a field-specific standard when one applies.

Yes. When light enters glass (n = 1.5), its speed drops to c / n and the wavelength drops by the same factor, but frequency stays the same. The calculator assumes vacuum/air by default. Override v if you are working inside a denser medium.