Frequency Converter

Frequency describes how often a periodic process repeats per unit of time. The SI unit of frequency is the hertz (Hz), named after Heinrich Rudolf Hertz, the German physicist who first generated and detected radio waves experimentally in 1886. 1 Hz means exactly one event per second. The reciprocal of frequency is the period: T = 1/f. At a mains frequency of 50 Hz, one oscillation takes exactly 1/50 of a second, i.e. 20 milliseconds.

In electronics and computing, kilohertz (kHz), megahertz (MHz) and gigahertz (GHz) are the common units. Modern computer processors run at clock speeds of 3–5 GHz – that means 3 to 5 billion clock cycles per second. WLAN routers transmit on 2.4 GHz and 5 GHz. USB 3.0 transfers data at a 5 GHz clock rate. RAM modules have clock frequencies of 2,400–6,400 MHz. Quartz oscillators in clocks typically vibrate at 32,768 Hz (2¹⁵ Hz), which produces a second-accurate tick through frequency division.

In radio and mobile communications, frequency bands are precisely defined. FM radio: 87.5–108 MHz. DAB+ digital radio: 174–230 MHz. GSM (2G): 900 and 1,800 MHz. LTE (4G): 700 MHz to 2.6 GHz. 5G-NR: 600 MHz to 100 GHz (sub-6 GHz and millimetre waves). WLAN at 2.4 GHz has better range than 5 GHz WLAN, which in turn allows higher data rates. Bluetooth also uses the 2.4 GHz band with frequency hopping.

Revolutions per minute (RPM) is technically also a frequency: 1 RPM = 1/60 Hz. RPM is used for rotating machinery such as motors, gearboxes, fans and turbines. Car engines idle at 700–900 RPM and reach 4,000–7,000 RPM at maximum power. Power tool motors can reach 30,000 RPM (e.g. a Dremel). Hard disk drives spin at 5,400 or 7,200 RPM. Turbochargers reach up to 300,000 RPM.

In audio, frequency is given in Hz. The human ear perceives frequencies from about 20 Hz to 20,000 Hz. Below 20 Hz is called infrasound, above 20,000 Hz ultrasound. The note A4 (concert pitch) is exactly 440 Hz – the international standard since 1939. Bass tones: 20–250 Hz. Mids: 250–4,000 Hz. Highs: 4,000–20,000 Hz. Medical ultrasound (sonography) uses 1–20 MHz, while industrial ultrasound for welding and cleaning uses 20–60 kHz. With our frequency converter you can convert all units quickly and precisely.