Revolutions per minute

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Revolutions per minute (abbreviated rpm, RPM, r/min, or min⁻¹) is a unit of frequency, commonly used to measure rotational speed, in particular in the case of rotation around a fixed axis. It represents the number of full rotations something makes in one minute. The International System of Units (SI) unit for rotational velocity is the radian per second (rad·s⁻¹).

Examples

• An automobile's engine typically varies between 700 and 7000 rpm.
• A piston aircraft engine typically rotates between 2000 and 3000 rpm.
• A racing car engine's limits is close to 20,000 rpm in Formula One.
• Gas turbine engines rotate at tens of thousands of rpm. JetCat model aircraft turbines are capable of over 100,000 rpm with the fastest hitting 165,000 rpm.

Symbols other than RPM

Standards organizations generally recommend the symbol r/min, which better follows the general principles for forming unit symbols. But this is not enforced in fully metric countries as an international standard; for example, the French use the symbol tr/mn ('tours par minute').