Revolutions per minute

Revolutions per minute
Unit ofRotational speed
Symbolrpm or r/min
1 rpm in ...... is equal to ...
   SI units   2π/60 rad s−1 = 0.1047 rad s−1
Revolution per minute
Unit ofRotational frequency
Symbolrpm or r/min
1 rpm in ...... is equal to ...
   SI units   1/60 Hz = 0.016 Hz
   SI base units   0.016 s−1

Revolutions per minute (abbreviated rpm, RPM, rev/min, r/min, or with the notation min−1) is a unit of rotational speed or rotational frequency for rotating machines.


ISO 80000-3:2019 defines a unit of rotation as the dimensionless unit equal to 1, which it refers to as a revolution, but does not define the revolution as a unit. It defines a unit of rotational frequency equal to s−1.[1] The superseded standard ISO 80000-3:2006 did however state with reference to the unit name 'one', symbol '1', that "The special name revolution, symbol r, for this unit is widely used in specifications on rotating machines."

A corresponding but distinct quantity for describing rotation is angular velocity, for which the SI unit is the radian per second.

Although they have the same dimensions (s−1), hertz (Hz) and radian per second (rad/s) are two different units and are used to measure two different but proportional ISQ quantities: frequency and angular frequency (angular speed, magnitude of angular velocity) respectively. The conversions between a frequency f and an angular velocity ω are:

Thus a disc rotating at 60 rpm is said to have an angular speed of 2π rad/s and a rotation frequency of 1 Hz.

The International System of Units (SI) does not recognize rpm as a unit. It defines units of angular frequency and angular velocity as rad s−1, and units of frequency as Hz, equal to s−1.


See also[]


  1. ^ ISO 80000-3:2019
  2. ^ a b "Physical parameters". DVD Technical Notes. Moving Picture Experts Group (MPEG). 1996-07-21. Archived from the original on 2012-02-19. Retrieved 2008-05-30.
  3. ^ Chichester, Ryan (June 10, 2021). "The Athletic's Eno Sarris talks Spider Tack, Gerrit Cole with Moose & Maggie". WFAN. Retrieved June 14, 2021 – via
  4. ^ "2014 season changes". Formula One. Retrieved 2014-08-18.
  5. ^ "Double-Density Versus High-Density Disks". Apple. Retrieved 2012-05-05.
  6. ^ "Slender and Elegant, It Fuels the Bomb". The Electricity Forum. Retrieved 2006-09-24.
  7. ^ "P60-SE Special Edition". JetCat USA. Archived from the original on 2012-04-19. Retrieved 2006-07-19.
  8. ^ Post, Richard F. (April 1996). "A New Look at an Old Idea: The Electromechanical Battery" (PDF). Science & Technology Review. University of California: 12–19. ISSN 1092-3055. Retrieved 2008-05-30.
  9. ^ Magariyama, Y.; Sugiyama, S.; Muramoto, K.; Maekawa, Y.; Kawagishi, I.; Imae, Y.; Kudo, S. (October 27, 1994). "Very fast flagellar rotation". Nature. 371 (6500): 752. Bibcode:1994Natur.371..752M. doi:10.1038/371752b0. PMID 7935835.