Calculate frequency from either a period or a wavelength and wave velocity. Enter your period (T) in any time unit, or provide a wavelength (λ) alongside a wave velocity (v) — choose from presets like light in a vacuum or sound in air. Get back the frequency in Hz, plus convenient conversions to kHz and MHz.
Frequency (Hz)
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Frequency (kHz)
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Frequency (MHz)
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Frequency (GHz)
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Period (s)
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Angular Frequency (ω)
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Frequency is the reciprocal of the period: f = 1 / T. If a wave completes one full cycle every 0.01 seconds, its frequency is 1 / 0.01 = 100 Hz. Simply divide 1 by the period expressed in seconds to get frequency in hertz.
Use the formula f = v / λ, where v is the wave velocity in m/s and λ is the wavelength in meters. For example, if light travels at ~300,000,000 m/s and the wavelength is 500 nm (500 × 10⁻⁹ m), the frequency is approximately 6 × 10¹⁴ Hz.
Frequency and wavelength are inversely proportional for a given wave speed: f = v / λ. As frequency increases, wavelength decreases, and vice versa. This relationship holds for all wave types including electromagnetic and sound waves.
Frequency is measured in hertz (Hz), where 1 Hz equals one complete cycle per second. Larger units include kilohertz (kHz = 10³ Hz), megahertz (MHz = 10⁶ Hz), and gigahertz (GHz = 10⁹ Hz), commonly used for radio, audio, and computing applications.
Angular frequency (ω) measures how fast an oscillation progresses in radians per second. It relates to regular frequency by ω = 2πf. It is commonly used in physics and engineering when working with sinusoidal signals and oscillating systems.
5G networks operate across a wide spectrum. Sub-6 GHz 5G uses frequencies between about 600 MHz and 6 GHz, while mmWave 5G operates between roughly 24 GHz and 100 GHz. The exact frequency depends on the band and country-specific allocations.
Violet light has the highest frequency in the visible spectrum, at approximately 668–789 THz (terahertz), corresponding to wavelengths around 380–450 nm. Red light sits at the opposite end with the lowest visible frequency, around 400–484 THz.
For photons (electromagnetic radiation), energy is directly proportional to frequency: E = h × f, where h is Planck's constant (6.626 × 10⁻³⁴ J·s). Higher frequency means higher energy — which is why ultraviolet and X-ray radiation are more energetic than visible light.