Frequency, Period & Wavelength Converter

Free tool to convert Hz, milliseconds and the wavelength of sound in metres and feet. No sign-up

Type a value and choose its unit, or load a common frequency like 20 Hz or 1 kHz.
Set the air temperature (20 °C by default): it changes the speed of sound and so the wavelength.
Set the sample rate if you want the samples per cycle.
Read the table: your unit is highlighted, with frequency, period, wavelength in metres, centimetres, feet and inches, and half and quarter wavelength.
Download the results as CSV or copy them as text.

Choose the unit of the value you type and every other quantity is calculated; changing the unit converts the value already in the box. Wavelengths are for sound in air at the temperature you set, and the row of the unit you chose is highlighted.

Nothing is saved or uploaded: everything stays in your browser. Download or copy your results before closing the page. The speed of sound is c = 331.3 + 0.606 × temperature (°C), which is accurate for dry air and ignores humidity.

How do you convert frequency to wavelength and period for sound in air?

The wavelength is the speed of sound divided by the frequency, and the period is 1 divided by the frequency. At 20 °C the speed of sound is about 343.4 m/s, so 100 Hz has a wavelength of 3.43 m and a period of 10 ms, and 1 kHz has a wavelength of 34.3 cm and a period of 1 ms. The speed of sound rises by about 0.6 m/s for every degree, so temperature changes the wavelength by a few percent. This free converter turns any of these quantities into all the others, and also gives half and quarter wavelengths and the samples per cycle at your sample rate.

What are frequency, period and wavelength?

Sound is a vibration of the air that repeats over and over. Frequency is how many times it repeats per second, in hertz (Hz): low notes have low frequencies. Period is the time of one repetition, so a 100 Hz sound repeats every 10 milliseconds. Wavelength is the distance the sound travels during one period: bass has wavelengths of metres, treble of centimetres. This is why low frequencies are hard to absorb and spread around corners, while high frequencies are more directional, and why a quarter of a wavelength is a useful size for acoustic panels and speaker placement.

Made by Luca Martone, sound designer and live sound engineer based in Turin.
For more information, click on the logo below.