mHz

millihertz

Frequencyexact by definition

The millihertz is 10⁻³ hertz, one cycle every 1,000 seconds. It is the band of Earth's free oscillations after a great earthquake, of ocean tides expressed as frequencies, and of the space-based gravitational wave detectors designed to observe massive binaries.

Watch out: Its symbol mHz differs from megahertz MHz only in case, and the two are nine orders of magnitude apart. This is the single most damaging case-sensitivity trap in the SI prefixes, and the reason the unit id here is "millihz" rather than "mhz".

1 mHz 0.001 Hz