Frequency Calculator – Calculate Frequency from Period and More

Calculate signal frequency, period, and angular frequency with our frequency calculator. Covers Hz to period conversions and is useful for electronics, physics, and audio.

Calculation Mode

Period (seconds)

How to Use This Frequency Calculator

Select your calculation mode

Choose from three modes: calculate frequency from period (f = 1/T), from wavelength (f = v/λ), or calculate angular frequency from regular frequency (ω = 2πf).

Enter your known values

Depending on the mode, enter period in seconds, wavelength in meters with wave velocity, or frequency in Hz. The default velocity is the speed of light (3×10⁸ m/s).

View your results

The calculator displays frequency in appropriate units (Hz, kHz, MHz, or GHz), plus angular frequency and period where applicable.

Frequency Reference Table

Application	Frequency Range	Period
Human hearing (low)	20 Hz	50 ms
Human hearing (high)	20,000 Hz (20 kHz)	50 μs
AM radio	540-1600 kHz	0.6-1.9 μs
FM radio	88-108 MHz	9-11 ns
WiFi 2.4 GHz	2.4 GHz	0.42 ns
WiFi 5 GHz	5 GHz	0.2 ns
Visible light	430-770 THz	1.3-2.3 fs

Note: Hz = cycles per second, kHz = 1000 Hz, MHz = 1 million Hz, GHz = 1 billion Hz, THz = 1 trillion Hz

Understanding Frequency, Period, and Wavelength

Frequency and Period Are Inverses

Frequency (f) measures how many cycles occur per second. Period (T) measures how long one cycle takes. They are inverses: f = 1/T and T = 1/f. A 100 Hz signal completes 100 cycles per second, so each cycle takes 0.01 seconds (10 milliseconds).

Frequency and Wavelength Relationship

For waves, frequency relates to wavelength through velocity: f = v/λ. Higher frequency means shorter wavelength. Radio waves travel at light speed (3×10⁸ m/s), so a 100 MHz signal has a wavelength of 3 meters. Sound travels at about 343 m/s in air, so a 440 Hz musical note has a wavelength of about 0.78 meters.

Angular Frequency Explained

Angular frequency (ω, omega) measures rotation rate in radians per second instead of cycles per second. One cycle equals 2π radians, so ω = 2πf. Angular frequency is used in physics equations involving oscillation and rotation because it simplifies calculus. A 60 Hz AC power signal has an angular frequency of about 377 rad/s.

Tips for Frequency Calculations

Use scientific notation for extreme values

Radio frequencies are often in MHz or GHz. Write 2.4 GHz as 2.4e9 or 2400000000. Period values can be tiny: 1 nanosecond is 1e-9 seconds.

Know your wave velocity

Electromagnetic waves travel at light speed in vacuum (3×10⁸ m/s). Sound travels at 343 m/s in air at 20°C, about 1480 m/s in water. Use the correct velocity for accurate wavelength calculations.

Check unit consistency

If wavelength is in meters, velocity must be in meters per second. If you have wavelength in centimeters, convert to meters first (divide by 100) before calculating.

Remember the frequency spectrum

Audio: 20 Hz to 20 kHz. Radio: kHz to GHz. Light: hundreds of THz. If your result falls far outside the expected range, double-check your inputs.

Frequently Asked Questions

What is the formula for frequency?

The basic frequency formula is f = 1/T, where T is the period in seconds. For waves, frequency also equals velocity divided by wavelength: f = v/λ. Angular frequency is ω = 2πf, measured in radians per second instead of cycles per second.

How do I convert Hz to period?

Period is the inverse of frequency: T = 1/f. For 50 Hz, the period is 1/50 = 0.02 seconds (20 milliseconds). For 1 MHz (1,000,000 Hz), the period is 1/1,000,000 = 1 microsecond.

What is the difference between frequency and angular frequency?

Regular frequency (f) counts complete cycles per second in Hertz. Angular frequency (ω) measures radians per second. Since one cycle equals 2π radians, ω = 2πf. Angular frequency is preferred in physics because it eliminates factors of 2π from equations.

How do I find wavelength from frequency?

Use λ = v/f, where v is wave velocity. For electromagnetic waves in air or vacuum, v ≈ 3×10⁸ m/s. A 100 MHz radio signal has wavelength λ = 3×10⁸ / 100×10⁶ = 3 meters. For sound in air at 20°C, use v ≈ 343 m/s.

What units are used for frequency?

The SI unit is Hertz (Hz), meaning cycles per second. Common multiples include kHz (1000 Hz) for audio, MHz (million Hz) for radio and processors, GHz (billion Hz) for WiFi and CPUs, and THz (trillion Hz) for infrared and visible light.

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