By Zencalcy Editorial TeamLast reviewed About us
Every sound wave obeys v = f λ. In air at room temperature a 440 Hz tone has a wavelength of about 78 cm, while 20 Hz stretches to 17 m. Wavelength matters for room acoustics, loudspeaker directivity and the size of instruments relative to the notes they produce.
Wavelength, frequency and speed of a sound wave.
v = f λ
v is the phase speed in the medium, f the frequency in hertz and λ the wavelength in metres. In air, v is about 343 m/s at 20 °C.
| Symbol | Meaning |
|---|---|
| v | Speed of sound in the medium. |
| f | Frequency. |
| λ | Wavelength. |
λ = 343 / 440 = 0.780 m. A 20 Hz tone has λ = 17.2 m, and a 20 kHz tone has λ = 17.2 mm, which is why high frequencies are easily blocked by small objects.
Continue with the Acoustic Impedance Calculator, Beat Frequency Calculator, or the Decibel Addition Calculator — or browse more acoustics and sound tools and all physics calculators.
For a fixed frequency, yes. The sound speed rises with temperature, so the wavelength grows in proportion. Frequency is set by the source and stays the same.
Results are computed from the standard equations of classical mechanics. Unit conversions use the SI definitions published by NIST. Air resistance is ignored unless the calculator names a drag model.
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Content updated: September 2026