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Unit Equal to:
Kilohertz 1000 Hz
Megahertz 1000 kHz
Gigahertz 1000 MHz
Terahertz 1000 GHz
Petahertz 1000 THz
Exahertz 1000 PHz
Zettahertz 1000 EHz
Yottahertz 1000 ZHz

The hertz (symbol: Hz) is a unit time to measure frequency. It tells how often something happens. A frequency of 1 hertz means that something happens once a second. The pitch of the note Middle C (the C in the middle of the piano) is 262 Hz. This means there are 262 vibrations every second when a Middle C is played. Humans ability to hears sounds is somewhere between 20-20 000 Hz.Owl ability to hears sounds is somewhere between 20-120000 Hz.

The unit is named after Heinrich Rudolf Hertz.

Bigger units

1000 hertz equals 1 kilohertz. 1000 kilohertz equals 1 megahertz, 1000 megahertz equals 1 gigahertz and so on.


  • The frequency of the Earth's spinning (once per ~24 hours) is about 12 microhertz (much smaller than 1 Hz).
  • The hertz is sometimes used to measure the power of a processor in computing and electronics.