Use the formula: wavelength = speed of wave / frequency
For light and other electromagnetic waves in vacuum, use: wavelength = 299,792,458 / frequency
Make sure frequency is in hertz (Hz)
Make sure wavelength is in meters (m)
Divide the wave speed by the frequency
Example: if frequency = 5 × 10^14 Hz, wavelength = 299,792,458 / (5 × 10^14)
Convert the result to the desired unit if needed
Use a lower wave speed if the wave is not traveling in vacuum