Frequency Calculator
Calculate frequency from period (f = 1/T) or from wave speed and wavelength (f = v/λ). Results in Hz, kHz, MHz.
FREQUENCY
50 Hz
PERIOD
0.02 s
IN mHz
50,000 mHz
FORMULA
f = 1/T
💡 How to Calculate Frequency
What Is Frequency?
Frequency measures how often a repeating event occurs per unit of time. In physics, it is the number of complete cycles of a wave or oscillation that occur per second. The SI unit of frequency is the hertz (Hz), where 1 Hz equals one cycle per second.
Frequency is used to describe sound waves, light waves, radio signals, alternating current (AC), and any periodic motion. It is closely related to wavelength and wave speed through the wave equation.
How to Calculate Frequency
Frequency from Period
If you know the period (the time for one complete cycle), you can find frequency using:
Where f is frequency in hertz and T is the period in seconds. For example, if a pendulum completes one swing every 2 seconds, its frequency is f = 1/2 = 0.5 Hz.
Frequency from Wave Speed and Wavelength
For any wave, the frequency is related to the wave speed and wavelength by:
Where v is the wave speed (m/s) and λ is the wavelength (m). For sound in air at room temperature (v ≈ 343 m/s), the concert pitch A has a frequency of 440 Hz and a wavelength of λ = 343/440 = 0.78 m.
Common Frequency Ranges
Human hearing ranges from about 20 Hz to 20,000 Hz. The AM radio band is 535–1,605 kHz. FM radio is 88–108 MHz. Wi-Fi operates at 2.4 GHz or 5 GHz. US household electricity alternates at 60 Hz.