Short for Revolutions Per Minute, RPM is used to help determine the access time on computer hard drives. RPM is a measurement of how many revolutions a computer's hard drive makes in a single minute. The higher the RPM, the faster the data will be accessed; for example, if you were comparing two hard drives, one with 5400 RPM and another with 7200 RPM, the hard drive with a 7200 RPM will be capable of accessing data much faster than the other.