Revolutions per minute

rpm redirects here. For other uses, see rpm (disambiguation)

For the Rise Against album, see Revolutions Per Minute (album).

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.

Examples

Gramophone (phonograph) records typically rotate steadily at 16, 33⅓, 45 or 78 rpm.
Audio CD rotation rates vary from about 500 rpm when reading the innermost data track, to 180 rpm when reading tracks near the outer edge.
The sweep second hand of a clock or watch rotates at 1 rpm.
A washing machine's drum may rotate at 500 to 1800 rpm during the spin cycles (depending on brand/model).
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 are much higher, as high as 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 ^*
A computer's hard drive rotates at 3600, 4200, 5400, or 7200 rpm on IDE types and 10,000 or 15,000 rpm on some SATA and SCSI and Fibre Channel drives.
A 52× CD-ROM drive can rotate a CD as fast as 10,350 rpm.
A Zippe-type centrifuge for enriching uranium spins at 90,000 rpm or faster.

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').

Compared to frequency and angular speed

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

1 r/min = 1/60 Hz

This is often used for measuring waves, such as radio and sound.

The SI unit of angular speed is the radian per second:

1 rev/min = 2π rad·min⁻¹ = 2π/60 rad·s⁻¹ = 0.10471976 rad·s⁻¹

However, there is no movement to use either of these units of measure (which are primarily used in physics) to replace revolutions per minute when measuring the rotational speed of machinery.

Gourt Home::Gourt :: Revolutions per minute

Examples

Symbols other than RPM

Compared to frequency and angular speed

See also