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 megahertz (MHz) equals one million hertz, widely used for radio frequency bands, early CPU clock speeds, and wireless communication standards. FM radio broadcasts in the 88–108 MHz range, while early personal computers operated at just a few MHz. One megahertz equals 1,000,000 cycles per second.