Frequency Converter - Hz, kHz, MHz, GHz, RPM

About this tool

The frequency converter maps between Hz, kHz, MHz, GHz and THz, plus RPM (rotations per minute), BPM (beats per minute in music) and angular frequency (rad/s). Useful for audio production (BPM analysis), radio frequencies (FM, WiFi, 5G), CPU clocks, motors, oscilloscope reading, and computing wavelength from frequency. Everything runs in the browser and all values update in real time.

How to use it

1. Type a value in any field (Hz, kHz, MHz, GHz or THz).
2. See all other units update instantly.
3. Switch to the BPM or RPM tab for music tempo or motors.
4. See wavelength and period automatically calculated below.

Examples

Common use cases

• Audio production: converting BPM to Hz for LFO modulation (120 BPM = 2 Hz).
• Radio and TV: FM 87.5–108 MHz, DAB 174–240 MHz, TV UHF 470–698 MHz.
• Wireless: WiFi 2.4/5/6 GHz, Bluetooth 2.4 GHz, 5G at 3.5 GHz and 28 GHz.
• Mechanical: converting motor RPM to Hz for vibration analysis.
• Physics work: computing wavelength from frequency (λ = c/f) for sound and light.

Frequently asked questions

What is one Hertz exactly?

One Hertz (Hz) is one cycle per second. The unit is named after Heinrich Hertz, who proved the existence of electromagnetic waves in 1887. One Hz can be one sound oscillation, one motor rotation, or one radio wave per second. All periodic phenomena are measured in Hz.

Why does Europe use 50 Hz and the US 60 Hz?

Pure historical choice. Westinghouse in the US picked 60 Hz in the late 1800s, while AEG in Germany went with 50 Hz. Both work, but 60 Hz gives less visible light flicker and slightly less motor material (motors run faster), while 50 Hz gives slightly lower core losses in transformers. The standards spread through colonisation and trade: 50 Hz in Europe, Asia, Africa, most of Australia; 60 Hz in North America, parts of South America, and Japan (where half the country is 50 Hz, half is 60 Hz).

What is the human hearing range?

Adults typically hear 20 Hz to 20 kHz. Children can hear higher frequencies (up to 22–23 kHz), and the ceiling drops with age (presbycusis). Musicians and audio engineers are especially sensitive in the 2–5 kHz range where voices and speech clarity live. Digital audio uses 44.1 kHz or 48 kHz sample rates, which per Nyquist covers frequencies up to 22 kHz.

How are frequency and wavelength related?

Via the formula λ = v/f, where v is the wave speed and f is the frequency. For light in vacuum v = c ≈ 299,792,458 m/s, so a 100 MHz radio wave has wavelength 2.998 m. For sound in air at 20°C, v ≈ 343 m/s, so 440 Hz has wavelength 78 cm. Antennas are often sized to a quarter or half wavelength, which is why 2.4 GHz WiFi antennas are small (12.5 cm/4 ≈ 3 cm).

Technical background

Frequency is the count of periodic events per time, measured in Hertz (Hz = 1/s). Period T is the time between two equivalent phase states: T = 1/f. Angular frequency ω is 2πf in radians per second, used in physics and electronics for sine waves and complex exponentials e^(jωt). SI prefixes: k = 10³, M = 10⁶, G = 10⁹, T = 10¹². Conversions: 1 Hz = 60 RPM = 60 BPM = 2π rad/s ≈ 6.283 rad/s. For waves: λ = v/f, where v is the medium’s wave speed (c in vacuum for EM radiation, ≈ 343 m/s for sound in air at 20°C). The Nyquist–Shannon theorem states that a signal of maximum frequency fmax can be reconstructed perfectly from samples taken at least at 2·fmax; that’s why CD audio uses 44.1 kHz sampling for human hearing up to 22 kHz. FM radio is 87.5–108 MHz, DAB 174–240 MHz, WiFi 2.4/5/6 GHz, 4G 700–2600 MHz, 5G up to 26–28 GHz mmWave. The tool uses double-precision floating point (JavaScript’s Number), which keeps at least 15 decimal digits and supports numbers up to 1.7·10³⁰⁸.