RPM is an acronym standing in for “revolutions per minute,” and is a standard measurement for the frequency of rotation in most modern vehicles. An RPM meter is almost always included on a vehicle’s dashboard and can be used to assess a variety of different things under the hood.
RPM in a nutshell
In general, your RPM meter is measuring how often components in your engine are rotating - chief among them your crankshaft. RPM meters typically measure in thousands, so a “2” on the meter would mean “2,000 revolutions per minute.”
On average, the higher your RPM meter, the higher the stress on your engine components. The RPM measurement is particularly important to drivers of manual shift cars, as it serves as a great indicator of when to shift up-gear.
Using RPM to check the health of your engine
Your vehicle’s RPM gauge can be used as a useful indicator of problems with the transmission of your vehicle. In particular, a surging RPM meter is almost always a bad sign and can indicate greater problems with the fuel injection systems of your vehicle.
Typically, your RPM should directly reflect how much gas you’re giving the vehicle. Of course, an up-shift will lessen the RPM, but an initial petal press should push the needle on the meter up accordingly. If it doesn’t match up, it could be an indicator of a failing clutch in your transmission.
RPM meter = Tachometer
While this is immediately known by a life-long mechanic, it might surprise the occasional grease-monkey that a RPM meter and a tachometer are the exact same thing. Tachometers aren’t only used on vehicles either - computer hard disks also use them to measure the RPM of the disk inside the casing.