Revolutions per minute (abbreviated rpm, RPM, rev/min, r/min, or with the notation min^{−1}) is the number of turns in one minute. It is a unit of rotational speed or the frequency of rotation around a fixed axis.
Revolutions per minute  

Unit of  Rotational speed 
Symbol  rpm or r/min 
Conversions  
1 rpm in ...  ... is equal to ... 
SI units  1/60 Hz = 0.016 Hz 
SI base units  0.016 s^{−1} 
ISO 800003:2019 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 also defines a unit of rotational frequency equal to s^{–1}.^{[1]}
The International System of Units (SI) does not recognize rpm as a unit, and defines the unit of frequency, Hz, as equal to s^{–1}.

A corresponding quantity is angular velocity, for which the SI unit is the radian per second. It is typically given the symbol ω or Ω.
Although they have the same dimensions (s^{−1}), hertz (Hz) and radian per second (rad/s) are two different units, representing two different but proportional ISQ quantities: frequency and angular frequency (angular speed, magnitude of angular velocity). The conversions between a frequency f (measured in hertz) and an angular velocity ω (measured in radians per second) are:
Thus a disc rotating at 60 rpm is said to be have an angular speed of 2π rad/s and a rotation frequency of 1 Hz.