Hertz (Hz)
The SI unit of frequency: one cycle per second. Named after Heinrich Hertz.
The hertz is the reference unit for frequency on this site.
About the hertz
Heinrich Rudolf Hertz (1857 to 1894) was a German physicist who, in experiments between 1886 and 1889, produced and detected radio waves with a spark-gap transmitter and a loop receiver. He showed that they travel at the speed of light and can be polarised, reflected and refracted, confirming Maxwell's theory. Asked about uses for them, he is said to have replied, Nothing, I guess. The International Electrotechnical Commission established the name hertz in 1935, and the CGPM adopted it in 1960, replacing cycles per second.
One hertz is one cycle per second, equal to s to the minus one. A clock ticking once a second runs at 1 Hz, a human heart at rest beats at around 1.2 Hz, and young ears hear roughly 20 Hz to 20,000 Hz. The SI treats cycle itself as not a unit, and the hertz applies only to periodic events, whereas the becquerel counts random radioactive decays, even though both are one per second. The second is now defined by fixing the caesium frequency at exactly 9,192,631,770 hertz.
Sources: Wikipedia: Hertz; Wikipedia: Heinrich Hertz; BIPM: SI Brochure, 9th edition
Hertz conversion chart
1 hertz expressed in every other frequency unit:
| Unit | 1 hertz |
|---|---|
| Kilohertz | 0.001 |
| Megahertz | 0.000001 |
| Gigahertz | 1×10⁻⁹ |
| Revolutions Per Minute | 60 |
| Beats Per Minute | 60 |
| Terahertz | 1×10⁻¹² |
| Millihertz | 1,000 |
| Radians Per Second | 6.283185307 |
| Degrees Per Second | 360 |
More Metric (SI) units
- kilohertz (frequency)
- megahertz (frequency)
- gigahertz (frequency)
- terahertz (frequency)
- millihertz (frequency)
- revolution per minute (frequency)
- beat per minute (frequency)
- meter (length)
- kilometer (length)
- centimeter (length)
- millimeter (length)
- micrometer (length)
- nanometer (length)
- picometer (length)
- decimeter (length)
- hectometer (length)
Browse all frequency units.