A quick acoustics calculator that turns any sound frequency into a physical wavelength, with temperature-correct speed of sound in air and presets for water and steel. Wavelength is the foundation of room acoustics, speaker placement, mic technique, and absorber design — this tool makes it one input away.
How it works
Wavelength is the distance one cycle of a wave occupies as it travels through a medium:
λ = c / f
where λ is the wavelength, c is the speed of sound in the medium, and f is the frequency in hertz. In air the speed of sound varies with temperature, which the calculator models with the standard dry-air relation:
c = 331.3 + 0.606 × T (metres per second, T in °C)
So a 1 kHz tone in 20 °C air, where c ≈ 343.4 m/s, has a wavelength of
343.4 / 1000 ≈ 0.343 m (about 13.5 inches). The same frequency in fresh
water (c ≈ 1481 m/s) stretches to 1.48 m.
Worked example
A 50 Hz bass note in a 21 °C control room:
- Speed of sound:
331.3 + 0.606 × 21≈ 344.0 m/s - Wavelength:
344.0 / 50= 6.88 m (22.6 ft) - Quarter wavelength: 1.72 m — a porous bass trap would need to be impractically deep to absorb 50 Hz fully, which is why low-frequency control relies on tuned traps and room geometry rather than thin foam.
Why wavelength matters
- Speaker boundary interference. A speaker a quarter wavelength from a wall creates a cancellation null at that frequency; the tool’s quarter-wavelength output predicts the problem frequency for a given distance.
- Absorber thickness. Broadband porous absorbers work down to the frequency whose quarter wavelength matches their depth.
- Mic spacing and comb filtering. Path-length differences comparable to a wavelength create comb-filter notches; knowing the wavelength tells you the spacing to avoid.
Every calculation runs locally in your browser; nothing is uploaded.