Scientists use the hertz unit to measure the frequencies of many kinds of cyclic phenomena such as radio waves or the relatively slower vibrations in earthquakes. One hertz, abbreviated Hz, indicates a single cycle or vibration per second; 1,000 cycles per second is 1 kilohertz, or 1KHz, and 1,000,000 cycles per second is 1 megahertz, or 1 MHz. Using simple arithmetic, you can convert frequencies in hertz to milliseconds of time.
To convert hertz to milliseconds, first determine the duration or period of one vibration by dividing one second by the frequency in hertz. For example, for a 500 Hz signal, the duration of one cycle is 1/500 or .002 seconds. To convert this figure to milliseconds, multiply it by 1,000. From the example, .002 seconds * 1,000 = 2 milliseconds. Each cycle in a 500 Hz signal takes 2 milliseconds to complete.