This page contains a frequency calculator, as well as calculators
with the equation rearranged to make speed and wavelength the
subject. The formulas are shown together with other useful
information and examples to try. Unit converters (feet to metres
and so on) can be found here (opens in a new tab).
Note that when considering electromagnetic radiation, such as
light, the quantity speed is usually denoted by the letter c, but
otherwise the letter v (standing for velocity) is usually used. We
will use v on this page in all cases, which is measured in metres
per second (m/s).
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Frequency (f)
The equation for frequency is given on the below.
Example: A particular AM radio station uses a wavelength of 250
metres. What frequency do we need to tune our receiver to in
order to hear the broadcast?
Radio waves travel at the speed of light, so in this case v is
equal to 299,792,458 metres per second (m/s). Putting these
figures (without commas) into the calculator above shows that
we need to tune the radio receiver to 1199.2 kHz (or 1.1992
MHz), which is around the middle of the medium wave (MW)
band.
Wavelength (λ)
The equation for wavelength is given below.
Example: Microwave ovens use electromagnetic radiation with a
frequency close to 2.45 GHz to heat up food. What is the
wavelength of the radiation?
Radio waves travel at the speed of light, so in this case v is equal
to 299,792,458 metres per second (m/s), and 2.45 GHz is
2,450,000,000 Hz, so that’s the frequency. Putting these figures
(without commas) into the calculator above shows that the
wavelength is 0.122 metres, or 12.2 centimetres.
The equation for wavelength is:
Where:
λ = wavelength (m)
v = velocity (m/s, ms
-1
)
f = frequency (s
-1
, or Hz)
 
Velocity (v)
The equation for velocity is given below.
Example: Sound travels in waves and does so at a particular
speed depending on what it is travelling through, such as air,
brick or water.
To find the speed of sound in air we can note that the musical
note A above middle C has a frequency of 440 Hz and a
wavelength of 0.773 metres. Putting these figures into the
calculator above shows that the speed of sound in air is close
to 340.1 meters per second.
 
The equation for velocity is:
Where:
v = velocity (m/s, ms
-1
)
f = frequency (s
-1
, or Hz)
λ = wavelength (m)
Frequency, speed and wavelength calculators