The kilohertz (kHz) equals 1,000 hertz, commonly used to describe audio frequencies, radio broadcasting bands, and early computer processor speeds. Human hearing ranges from about 20 Hz to 20 kHz, making this unit essential in audio engineering and music production. One kilohertz equals 1,000 cycles per second.

The gigahertz (GHz) equals one billion hertz, the standard unit for modern CPU clock speeds, Wi-Fi frequencies, and 5G cellular bands. A typical laptop processor runs at 2–5 GHz, while Wi-Fi operates at 2.4 GHz or 5 GHz. One gigahertz equals 1,000 megahertz or one billion cycles per second.