How do I convert frequency to wavelength?

Divide the wave speed by the frequency. For electromagnetic waves that is 299,792,458 m/s, so a 100 MHz FM signal has a wavelength of about 3 metres.

What is the relationship between frequency and period?

They are reciprocals: period equals one over frequency. A 50 Hz supply has a 20 millisecond period, and a 1 kHz tone repeats every millisecond.

Why is WiFi 2.4 GHz wavelength 12.5 cm?

Because 299,792,458 divided by 2.4 billion is about 0.125 metres. That wavelength is why WiFi antennas are a few centimetres long — antenna length is typically a half or quarter of the wavelength.

Does sound have a fixed speed?

No. It travels at about 343 m/s in air at 20°C and faster in warmer air, denser gases, liquids and solids. That is why the wavelength of a given note changes with room temperature.

What frequencies can humans hear?

Roughly 20 Hz to 20 kHz for a young adult, with the upper limit falling with age — most adults over forty cannot hear much above 15 kHz. That range corresponds to wavelengths from 17 metres down to 17 millimetres.

Frequency Calculator

Convert between frequency, period and wavelength for any wave speed.

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About the Frequency Calculator

Frequency, wavelength and wave speed are one relationship: v = fλ. For light in a vacuum the speed is exactly 299,792,458 metres per second — a defined constant since 1983, when the metre was redefined in terms of it rather than the other way round.

Period is simply the reciprocal of frequency. A 50 Hz mains supply has a period of 20 milliseconds; a 2.4 GHz WiFi signal has a period of about 417 picoseconds and a wavelength of 12.5 centimetres, which is why WiFi antennas are the size they are.

Sound is the case where the speed is not a constant. It travels at about 343 m/s in air at 20°C and faster when warmer, so a musical frequency's wavelength changes with the temperature of the room — which is why wind instruments go sharp as they warm up.

How it works

Enter any one of frequency, period or wavelength.
Pick the medium — light in vacuum or sound in air — or type your own wave speed.
The other two update immediately, with the band the frequency falls in.

Frequently asked questions

How do I convert frequency to wavelength?: Divide the wave speed by the frequency. For electromagnetic waves that is 299,792,458 m/s, so a 100 MHz FM signal has a wavelength of about 3 metres.
What is the relationship between frequency and period?: They are reciprocals: period equals one over frequency. A 50 Hz supply has a 20 millisecond period, and a 1 kHz tone repeats every millisecond.
Why is WiFi 2.4 GHz wavelength 12.5 cm?: Because 299,792,458 divided by 2.4 billion is about 0.125 metres. That wavelength is why WiFi antennas are a few centimetres long — antenna length is typically a half or quarter of the wavelength.
Does sound have a fixed speed?: No. It travels at about 343 m/s in air at 20°C and faster in warmer air, denser gases, liquids and solids. That is why the wavelength of a given note changes with room temperature.
What frequencies can humans hear?: Roughly 20 Hz to 20 kHz for a young adult, with the upper limit falling with age — most adults over forty cannot hear much above 15 kHz. That range corresponds to wavelengths from 17 metres down to 17 millimetres.

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