Frequency Converter

What Is Frequency?

Frequency is the number of complete cycles or oscillations that occur per unit of time. In physics and engineering, it describes how often a repeating event happens. A wave that completes one full cycle each second has a frequency of 1 hertz. A signal that cycles one million times per second has a frequency of one megahertz. Frequency is a fundamental property of waves, electromagnetic radiation, sound, AC electrical current, and rotating machinery.

Frequency and period are inversely related. Period is the time required for one complete cycle, measured in seconds. Frequency is 1 divided by the period. If a signal has a period of 0.001 seconds (1 millisecond), its frequency is 1000 Hz or 1 kHz. Understanding frequency is essential in electronics, audio engineering, telecommunications, medicine (MRI machines), and physics. For deeper physics problem-solving involving frequency, the free AI physics solver can work through wave and frequency equations step by step.

Frequency Units Explained

Hertz (Hz)

The hertz is the SI unit of frequency, named after German physicist Heinrich Hertz who proved the existence of electromagnetic waves in 1888. One hertz means one cycle per second. Hertz is used for very low frequency signals such as power grid AC frequency (50 Hz in Europe, 60 Hz in North America), audio bass tones (20–200 Hz), and brain wave activity measured by EEG equipment (1–30 Hz). The range of human hearing extends from approximately 20 Hz to 20,000 Hz.

Kilohertz, Megahertz, Gigahertz

Higher frequency applications use SI prefixed units for convenience. One kilohertz (kHz) equals 1,000 Hz and covers AM radio broadcasts (530–1700 kHz) and audio equipment specifications. One megahertz (MHz) equals 1,000,000 Hz and covers FM radio (87.5–108 MHz), television broadcasts, and older computer processor clock speeds. One gigahertz (GHz) equals 1,000,000,000 Hz and covers WiFi, Bluetooth (2.4 GHz), mobile data (4G/5G operates from 600 MHz to 70 GHz), and modern CPU speeds. One terahertz (THz) equals 10^12 Hz and covers infrared radiation, terahertz imaging systems used in medical scanning and security, and some experimental communication bands.

RPM and Radians Per Second

RPM (revolutions per minute) measures rotational frequency rather than wave frequency. It is commonly used for motors, engines, fans, and hard disk drives. To convert RPM to Hz, divide by 60. A motor spinning at 3600 RPM completes 60 revolutions per second, or 60 Hz. To convert to radians per second (rad/s), multiply Hz by 2π. Radians per second is the angular frequency unit used in physics and signal processing equations. For a 60 Hz signal: angular frequency = 60 × 2π = 376.99 rad/s. These rotational units are important for understanding centrifugal force, motor torque calculations, and signal phase in electrical engineering.

How to Convert Frequency Units

Frequency Conversion Table

Frequency and Wavelength Relationship

The Formula: Wavelength = Speed of Light / Frequency

For electromagnetic waves (radio, microwave, light, X-rays), wavelength and frequency are related by the speed of light:

• λ — Wavelength in meters
• c — Speed of light in vacuum: 299,792,458 m/s
• f — Frequency in hertz (Hz)

Higher frequency means shorter wavelength. Lower frequency means longer wavelength. Radio waves at 1 MHz have a wavelength of about 300 meters. Visible light at 500 THz has a wavelength of about 600 nanometers, which is the length of a few hundred atoms placed side by side. This inverse relationship is fundamental to understanding the electromagnetic spectrum and antenna design.

Wavelength Conversion Examples

Common Frequency Ranges

Radio Frequencies

The radio frequency (RF) spectrum is divided into named bands by ITU. AM radio occupies 530–1700 kHz (medium frequency, MF). FM radio occupies 87.5–108 MHz (very high frequency, VHF). Aviation communication and navigation systems use 108–137 MHz. Citizens band (CB) radio operates at 27 MHz in the high frequency (HF) band. Marine VHF radio uses 156–174 MHz. Amateur (ham) radio operators use many bands from 1.8 MHz through hundreds of GHz. Television broadcasts in the US use channels in the VHF (54–216 MHz) and UHF (470–698 MHz) bands.

Mobile cellular networks span a wide range. 2G GSM originally operated at 900 MHz and 1800 MHz. 3G UMTS added 850 MHz and 1900 MHz bands. 4G LTE operates across dozens of frequency bands from 700 MHz to 2.7 GHz. 5G sub-6 GHz networks use 600 MHz to 6 GHz, while 5G millimeter wave (mmWave) uses 24–100 GHz for extreme speed at short range. For frequency calculations involving electromagnetic theory, the chemistry AI solver can help with spectroscopy problems where frequency and wavelength are central.

Microwave Frequencies

Microwave frequencies range from 300 MHz to 300 GHz. Consumer microwave ovens operate at 2.45 GHz, which is in the ISM (Industrial, Scientific, and Medical) band. This frequency was chosen because it causes strong water molecule vibration that heats food. Radar systems operate across multiple microwave bands. Weather radar uses the S-band (2–4 GHz) and X-band (8–12 GHz). Police speed radar uses the K-band (18–27 GHz). Satellite communication and GPS operate in the L-band (1–2 GHz) and S-band. Point-to-point wireless backhaul systems for mobile networks use 6–80 GHz. Understanding large frequency numbers and their scientific notation is aided by the large numbers converter.

Visible Light Frequencies

Visible light occupies a very narrow band of the electromagnetic spectrum from approximately 380 THz (red edge) to 770 THz (violet edge). Red light sits at the low end, around 400–480 THz with wavelengths of 620–750 nm. Green light occupies 520–560 THz at 530–570 nm. Blue light ranges from 630–680 THz at 440–480 nm. Violet sits at the high end, around 700–770 THz at 390–430 nm. Beyond visible light, ultraviolet (UV) runs from 770 THz to 3 PHz. Infrared sits below red at 300 GHz to 400 THz. All of these are electromagnetic waves following the same wavelength-frequency relationship: wavelength = c / frequency.

Frequently Asked Questions