Sound Wavelength and Period Calculator

Wavelength equals the speed of sound divided by the frequency. At 20 C the speed of sound in air is about 343 metres per second, so a 440 Hz tone has a wavelength near 0.78 metres. Halve the frequency and the wavelength doubles.

In From temperature mode the calculator uses the dry-air formula: 331.3 times the square root of (1 + temperature in Celsius divided by 273.15) metres per second. Warmer air carries sound faster, which is why the wavelength for a fixed frequency grows a little as the room heats up.

The period is the time for one full cycle, equal to 1 divided by the frequency. The calculator shows it in milliseconds, so 440 Hz gives about 2.273 ms and a 20 Hz tone gives 50 ms. The period depends only on frequency, not on temperature or speed.

Yes. Click Set speed of sound and enter a value in metres per second. It overrides the temperature estimate, which is useful for water (about 1480 m/s), other gases, or a speed you measured. In that mode the temperature field is hidden.

Wavelength is inversely proportional to frequency, so as frequency falls the wavelength stretches. A 20 Hz tone spans roughly 17 metres in air, longer than most rooms, which is part of why deep bass is hard to control and needs large-scale room treatment.

The temperature mode defaults to 20 C, which yields about 343.21 m/s. This is the standard reference for room-temperature air. Change the temperature and the speed, and therefore the wavelength, updates with it.

The formula here covers dry air and temperature only. Humidity raises the speed of sound slightly and altitude changes it through temperature and composition, so for precise work in unusual conditions enter a measured speed in Set speed of sound mode.

The engine computes to six decimal places and the display rounds the wavelength and period to three decimals and the speed to two. So the shown values are accurate for practical acoustics; tiny differences from other calculators usually come from a different assumed speed of sound.

Wavelength guides speaker placement, standing-wave and room-mode analysis, the sizing of bass traps and diffusers, microphone spacing, and antenna-style spacing for arrays. Knowing the wavelength at a problem frequency tells you the physical scale you are dealing with.