Wavelength Calculator
Convert frequency to wavelength, half-wave and quarter-wave distances for any air temperature.
Inputs
Speed of sound: 343.4 m/s (768 mph)
The wave (2½ wavelengths)
How long is that?
That’s 1.83 sedan-lengths, or 4.8 people standing in a row.
How it works
A sound wave is a repeating pattern of high and low air pressure. The wavelength is the distance between two successive pressure peaks. It’s the speed of sound divided by the frequency.
λ = c / f T = 1 / f c ≈ 331.3 + 0.606 · T(°C) (≈ 343 m/s at 20 °C)
Bass waves are huge. A 40 Hz note is 8.6 m (28 ft) long, longer than most rooms and every car. That’s why bass is non-directional (you can’t tell where a sub is), why room acoustics dominate low-frequency performance, and why you need so much volume displaced to create it.
Fractions of a wavelength matter for design: a half-wave is the distance between standing-wave nodes (room mode spacing), a quarter-wave is the length at which a closed pipe or boundary resonates (L = λ/4) and is also where reflections from a nearby wall first cancel the direct sound. Sound is slightly faster in warm air: 1 m/s per 1.65 °C.