RPM - Revolutions Per Minute
Revolutions per minute is a measure of the frequency for a rotational component of a device along a fixed axis. The number of revolutions a rotational device completes in a minutes, is known as its RPM. It is commonly used to measure the rotational speed or angular velocity of some mechanical component.
RPM is measured for mechanical components like CD or DVD players, power generation turbine, piston of an automobile engine, turbocharger, Modern ultrasonic dental drills, aircraft engine, computer hard drive etc.
RPM - Revenue Per thousand iMpressions or Revenue Per Mille
(Mille is Latin for one thousand)
In term of Online Advertising, RPM refers to the revenue you earn per thousand page impressions.
RPM = (Estimated earnings / Number of page views) * 1000
For example, a website has earned Rs.200 from 2000 page views
RPM = (200 / 2000) * 1000
So, the Revenue per thousand impressions will be Rs.100 in this scenario.