Use the formula: wavelength = speed ÷ frequency
For electromagnetic waves in a vacuum, use: wavelength = 299,792,458 ÷ frequency
For sound waves or waves in a medium, use: wavelength = wave speed ÷ frequency
Measure frequency in hertz (Hz)
Measure wavelength in meters (m)
Measure wave speed in meters per second (m/s)
Rearrange the formula if needed: wavelength = v / f
Example: if frequency = 100 Hz and wave speed = 340 m/s, wavelength = 340 ÷ 100 = 3.4 m