Hertz to RPM: Converting Frequency Units
Frequency is how often something repeats. Hertz counts it per second and RPM per minute, so the whole conversion is a factor of 60. The Frequency Converter handles hertz, its prefixes and RPM.
The conversion
RPM to hertz: divide by 60. Hertz to RPM: multiply by 60. An engine at 3,000 RPM is turning at 50 Hz. A record at 33⅓ RPM is 0.56 Hz.
That is genuinely all there is to it. What causes confusion is not the arithmetic but which unit belongs where, and what the prefixes mean once the numbers get large.
Where each one is used
RPM is for things that physically rotate: engines, drills, hard drives, washing machine spin cycles, turntables. It is used because a minute is a human-scale interval for watching something spin.
Hertz is for waves and electronic signals: sound, radio, mains electricity, processor clocks, screen refresh rates. One hertz is one cycle per second.
The prefixes step by a thousand each time. A kilohertz is a thousand cycles a second, a megahertz a million, a gigahertz a billion. So a 3 GHz processor completes three billion clock cycles every second, and a 2.4 GHz wifi signal oscillates 2.4 billion times a second.
A few anchors worth having
Mains electricity is 50 Hz in Europe, most of Asia and Africa, and 60 Hz in North America and parts of Japan. That difference is why some older appliances ran at the wrong speed when taken across the Atlantic - a motor's speed is tied to the supply frequency.
Human hearing runs from about 20 Hz to 20,000 Hz, and the top of that range falls with age. Middle A on a piano is 440 Hz.
Screen refresh at 60 Hz redraws sixty times a second; 120 Hz twice that, which is what makes scrolling look smoother.
Hard drives at 7,200 RPM are 120 Hz, which is a reminder that the two units really are measuring the same quantity.
Where it gets subtle
A rotating thing has a frequency and also an angular velocity, which is measured in radians per second - and that is 2π times the frequency rather than equal to it, because one full turn is 2π radians. Engineering formulas use the radian version, which is why a figure can look like it is out by a factor of about 6.28. The Angle Converter covers why.
Sampling is the other one. To capture a sound wave faithfully you have to sample at more than twice its highest frequency, which is why CD audio is 44,100 Hz for a 20,000 Hz hearing range.
Common questions
How do I convert RPM to hertz?
Divide by 60. Nothing else is involved.
What does GHz mean on a processor?
Billions of clock cycles per second. It is not a direct measure of speed any more, since how much work happens per cycle varies by design.
Why is mains 50 Hz in some places and 60 in others?
Historical accident - competing early standards that both stuck.
Is RPM ever written as rev/min?
Yes, and in formal engineering work it often is. Same thing.
Got a frequency to convert?