Frequency Converter
By KAMP Inc. / UnitOwl · Last reviewed:
Frequency measures how often a repeating event occurs per unit time. It governs everything from the pitch of musical notes to the speed of computer processors to the wavelength of radio signals. The hertz (Hz) is the SI unit β one cycle per second β and from there the scale extends dramatically: audio spans 20 Hz to 20 kHz, radio waves range from kilohertz to gigahertz, and modern CPUs run at 3β5 GHz. Understanding frequency and its relationship to wavelength and period is fundamental to electronics, acoustics, and telecommunications.
Popular Frequency Conversions
Hertz, Kilohertz, Megahertz, Gigahertz
The hertz (Hz) honors Heinrich Hertz, who first demonstrated radio wave transmission in 1887. The metric prefixes scale it across many orders of magnitude: 1 kHz = 1,000 Hz; 1 MHz = 1,000,000 Hz; 1 GHz = 1,000,000,000 Hz. Human hearing spans approximately 20 Hz (very low bass) to 20,000 Hz (high-pitched squeal), though sensitivity diminishes above 15 kHz in adults. AM radio broadcasts in the 530β1,700 kHz band; FM radio in the 87.5β108 MHz band; Wi-Fi operates at 2.4 GHz and 5 GHz; 5G millimeter-wave uses 24β100 GHz. A modern CPU running at 3.6 GHz executes 3.6 billion clock cycles per second.
| Unit / Reference | Value |
|---|---|
| 1 kHz | 1,000 Hz |
| 1 MHz | 1,000,000 Hz |
| 1 GHz | 10βΉ Hz |
| Human hearing range | 20 Hz β 20 kHz |
| Middle C (musical note) | 261.63 Hz |
| A4 (concert pitch) | 440 Hz |
Frequency and Wavelength: The Inverse Relationship
Frequency and wavelength are inversely related through the speed of propagation: wavelength (Ξ») = speed (v) / frequency (f). For electromagnetic waves in a vacuum (radio, light, X-rays), the speed is c = 299,792,458 m/s. An FM radio signal at 100 MHz has a wavelength of 300,000,000 / 100,000,000 = 3 meters β which is why FM antennas are about 75 cm (a quarter-wavelength dipole). A 2.4 GHz Wi-Fi signal has a wavelength of about 12.5 cm; 5 GHz Wi-Fi has a 6 cm wavelength. Visible light at 600 nm (orange) corresponds to a frequency of about 500 THz. X-rays start around 30 petahertz (30 Γ 10ΒΉβ΅ Hz).
Period: The Reciprocal of Frequency
Period (T) is the time for one complete cycle, and is simply the reciprocal of frequency: T = 1/f. A 60 Hz AC power line completes one cycle every 1/60 β 16.67 milliseconds. A 440 Hz musical note completes one cycle every 2.27 milliseconds. A 3 GHz CPU clock cycle lasts 1/(3 Γ 10βΉ) β 0.333 nanoseconds. Period is relevant when analyzing waveforms on an oscilloscope, designing timing circuits, or calculating the time resolution of sampling systems. The Nyquist theorem states that to accurately represent a signal, you must sample it at least twice its highest frequency β a 20 kHz audio signal requires at least 40,000 samples per second, which is why CD audio uses a 44.1 kHz sample rate.
Sources & References
- NIST β Units and Conversion Factors β Official unit conversion factors from the National Institute of Standards and Technology.
- BIPM β The International System of Units (SI) β International SI unit definitions from the International Bureau of Weights and Measures.