Rpm

An acronym for 'revolutions per minute', rpm is a unit for rotational speed. Gramophone or analogue disc records typically rotate with 33, 45, or 78 rpm. Aircraft piston motors can rotate with 8000 rpm. An automobile's engine typically makes between 700 and 7000 rpm; a racing 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 rotational speed is the radian per second: 1 r/min = 0.104 719 76 rad/s.