Revolution Per Minute (rpm)
One 60th of a hertz. The unit for engine, motor and turntable speeds.
1 revolution per minute = 0.01666666667 hertz (approximately).
About the revolution per minute
Records gave rpm its fame. The 78 rpm speed was not chosen for a clear engineering reason; Wikipedia says it apparently happened to be the speed of one of the early machines, and the Gramophone Company formally set it as a recording standard in 1912. Columbia unveiled the 33 and a third rpm LP on 21 June 1948, and RCA Victor released the 45 rpm single in February 1949, starting a period called the War of the Speeds.
One rpm equals one sixtieth of a hertz, so a disc at 60 rpm turns at 1 Hz. The SI does not recognise rpm as a unit, preferring hertz or radians per second, and r/min is the usual symbol in standards. Typical examples are a modern car engine idling at about 750 to 900 rpm, consumer hard drives at 7,500 to 10,000 rpm, power-generation turbines at 3,000 or 3,600 rpm, and uranium centrifuges of the Zippe type at 100,000 rpm or more.
Sources: Wikipedia: Revolutions per minute; Wikipedia: Phonograph record
Revolution Per Minute conversion chart
1 revolution per minute expressed in every other frequency unit:
| Unit | 1 revolution per minute |
|---|---|
| Hertz | 0.01666666667 |
| Kilohertz | 0.00001666666667 |
| Megahertz | 1.666666667×10⁻⁸ |
| Gigahertz | 1.666666667×10⁻¹¹ |
| Beats Per Minute | 1 |
| Terahertz | 1.666666667×10⁻¹⁴ |
| Millihertz | 16.66666667 |
| Radians Per Second | 0.1047197551 |
| Degrees Per Second | 6 |
More Metric (SI) units
- hertz (frequency)
- kilohertz (frequency)
- megahertz (frequency)
- gigahertz (frequency)
- terahertz (frequency)
- millihertz (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.