# Rpm

*Alternate uses: rpm (disambiguation)*

**rpm**is a unit of frequency, commonly used to measure rotational speed. Gramophone or analogue disc records typically rotate with 33, 45, or 78 rpm. An automobile's engine typically makes between 700 and 7000 rpm. Aircraft piston motors can rotate with 8000 rpm. A racing car engine's limits are much higher, as high as 19,000 rpm in Formula 1. Gas turbine engines rotate at tens of thousands of rpm.

Standards bodies generally recommend the symbol 'r/min', which better follows the general principles for forming unit symbols.

The SI unit of frequency is the hertz (Hz):

- 1 rpm = 1 r/min = 1/60 Hz

- rotational speed = 1 rpm = 1 r/min -> angular speed = 0.104 719 76 rad/s.