Megahertz to Millihertz (MHz to mHz)

1 megahertz equals 1,000,000,000 millihertz exactly.

How to convert megahertz to millihertz

To convert megahertz to millihertz, multiply the number of megahertz by 1,000,000,000. This factor is exact. To go the other way, multiply millihertz by 1×10⁻⁹.

millihertz = megahertz × 1,000,000,000

Example: 10 megahertz = 10,000,000,000 millihertz.

About these units

Megahertz (MHz)

Metric (SI)Current unit

One million hertz. FM radio and older processors.

Engineers once said megacycles, and the older unit shows up in postwar papers, one 1946 study on ultrasound in liquids being titled with 15 megacycles. When hertz replaced cycles per second, the megacycle per second, Mc/s, became the megahertz. The word then entered home computing: Wikipedia notes personal computer clock speeds of around 1 MHz in the late 1970s on machines from Atari, Commodore and Apple.

A megahertz is one million hertz, the natural scale of broadcast radio. FM stations in most of the world use 87.5 to 108 MHz, with the Americas using 88 to 108 MHz and Japan using 76 to 95 MHz. In North America channels are spaced 200 kHz apart, and the FCC reassigned FM to its present band in 1945. As a way to rate computers, clock speed is criticised by many experts, who call it an easily manipulable benchmark because some chips need several cycles per operation and others perform several operations in one.

1 megahertz = 1,000,000 hertz (exactly).

Sources: Wikipedia: Megahertz; Wikipedia: FM broadcast band

Millihertz (mHz)

Metric (SI)Current unit

One thousandth of a hertz: one cycle every 1,000 seconds.

Millihertz describes oscillations so slow that a single cycle takes many seconds. One millihertz is 0.001 hertz, a period of 1,000 seconds, or about 16.7 minutes. At the other end of the scale, one revolution per minute works out to roughly 16.7 mHz, which is how a clock's second hand turns.

Slow phenomena are the natural home of the unit. The planned space-based gravitational-wave detector LISA is designed to operate from 0.1 to 10 mHz, a band that ground detectors cannot reach. The milli prefix is the SI factor of one thousandth, so a millihertz is a thousand times smaller than a hertz and a billion times smaller than a terahertz. Where signals are slower still, such as a daily cycle near 11.57 microhertz, microhertz take over.

1 millihertz = 0.001 hertz (exactly).

Sources: Wikipedia: Hertz; Wikipedia: Orders of magnitude (frequency); Wikipedia: Revolutions per minute

Related conversions

See all frequency units.