What does RPM stand for? In nearly every case it means revolutions per minute, the number of full turns something makes in one minute. It is how we measure spinning speed for car engines, washing machine drums, drills, fans, hard drives and record players.
If a dashboard needle points to 3, with "x1000 RPM" printed below, the engine's crankshaft is turning about 3,000 times a minute. The idea is simple, but the letters also appear in online ad reports and in health care with different meanings, so the setting matters.
Quick facts
Stands for
Revolutions per minuteType
Initialism, said R P MAlso written
rpm, r/minMeasures
Rotational speed, full turns each minuteSeen on
Tachometers, power tools, appliances, turntablesOther meanings
Revenue per mille, remote patient monitoringRelated terms
What does RPM stand for, letter by letter?
| Letter | Word | Meaning |
|---|---|---|
| R | Revolutions | Complete turns of 360 degrees |
| P | Per | For each |
| M | Minute | Sixty seconds |
One revolution is one full circle. So 60 rpm is one turn every second, and 600 rpm is ten turns every second. Engineers sometimes write the unit as r/min, while labels and dashboards usually print RPM or rpm. All of these name the same unit.
RPM in cars and engines
A tachometer, the gauge next to the speedometer, shows engine rpm, often in thousands. When a car idles at a stop light, the engine may turn somewhere around 600 to 1,000 rpm. Press the gas and the number climbs. The red zone at the top of the gauge, called the redline, marks the highest speed the engine is meant to reach.
From an owner's manual: "Shift to the next gear before the needle reaches the red zone." In other words, keep engine revolutions per minute below the safe limit printed on the gauge.
Higher rpm usually means more noise and more fuel used. Automatic transmissions shift gears to keep the number in a useful range, and the PRNDL shifter lets you pick the mode.
Other places you see RPM
- Records: turntables play at 33 1/3, 45 or 78 rpm. Full length albums on an LP spin at 33 1/3.
- Washing machines: a higher spin speed squeezes more water out of clothes.
- Power tools: drills and saws list a no load speed in rpm.
- Computer drives: spinning hard drives are often rated at 5,400 or 7,200 rpm.
- Exercise bikes: some screens show pedal speed, called cadence, in rpm.
RPM stands for more than spin speed
| Field | Stands for | Example |
|---|---|---|
| Online video and ads | Revenue per mille (per thousand views) | "Our RPM went up this month." |
| Health care | Remote patient monitoring | A home blood pressure cuff that sends readings to a clinic |
| Road work | Raised pavement marker | The small reflectors glued to lane lines |
Revenue per mille is a cousin of CPM. CPM is what an advertiser pays per thousand views, while RPM is what a creator or site earns per thousand. On health forms, remote patient monitoring means a doctor tracks some readings from your home.
RPM in sentences
- "The fan has three speeds, up to 1,200 rpm."
- "Keep the engine under 4,000 RPM for the first few hundred miles."
- "Set the turntable to 45 rpm for that single."
- "The channel's RPM dropped after the holidays."
Say each letter, "R P M." Use "an" in front, since R sounds like "ar": "an RPM gauge." Do not add an s; the letters already stand for a plural, so write "3,000 rpm," not "3,000 rpms."
Mix ups to avoid
RPM measures turning, not distance or rhythm. BPM, beats per minute, counts beats in music or a heart rate. Miles per hour measures how fast a vehicle moves, not how fast its engine spins. PSI measures pressure, as in tire pressure. You will find many more everyday short forms on the famous acronyms page.
Questions people ask
What does RPM mean in a car?
It is the number of times the engine's crankshaft turns each minute. The tachometer shows it, usually in thousands.
What is a normal RPM at idle?
Many car engines idle somewhere around 600 to 1,000 rpm, and it may run higher when the engine is cold. Your owner's manual gives the right range for your vehicle.
Is RPM capitalized?
Both RPM and rpm are common. Dashboards and labels often use capitals, while science and engineering writing often uses lowercase.
What does RPM mean on a record?
It tells you how fast the turntable must spin. Common speeds are 33 1/3, 45 and 78.
What is RPM in online video?
There it means revenue per mille, the money earned for every thousand views. It is different from CPM, which is what advertisers pay.