Method
Wavelength is the distance between matching points in a repeating wave, such as crest to crest. It equals wave speed divided by frequency.
Example
For sound traveling at 343 m/s with a frequency of 440 Hz, wavelength is 343 / 440 = 0.78 m. This is close to the wavelength of the musical note A4 in air at ordinary room conditions.
Common mistakes
Use hertz for frequency and a matching speed unit. Kilohertz, megahertz and meters per second must be converted consistently before comparing results.
Limitations
Wave speed depends on the medium. Sound in air, sound in water, radio waves and waves on a string all use different speed assumptions.
Last reviewed: 2026-05-17