Convert RPM to Hertz

About converting RPM to Hertz

RPM (rpm) and Hertz (Hz) are both units of frequency, so converting between them is a single multiplication: multiply your RPM figure by 0.01667. Ten RPM comes to 0.1667 Hertz, and a hundred works out at 1.6667 Hertz.

Rule of thumb: going from RPM to Hertz divides, so the figure always shrinks — it takes about 60 RPM to make a single Hertz. If your answer came out bigger, you have the conversion the wrong way round.

What is a RPM?

RPM measures rotation rather than waves, but a revolution is a cycle like any other, which is what puts it in the same family as the hertz. It is the number on a car’s tachometer, where an engine idles low and a redline marks the point past which the valvetrain will not keep up. It rated hard drives for decades — 5,400 and 7,200 rpm were the two grades of consumer drive, and the faster platter genuinely meant quicker access, a distinction SSDs made irrelevant. It is also the spin-cycle figure on a washing machine, where more rpm means drier clothes and more noise.

What is a Hertz?

The hertz is one cycle per second — nothing more. It is named after Heinrich Hertz, who demonstrated experimentally that electromagnetic waves exist, confirming what until then had been theory. The unit itself is younger than it looks: engineers said "cycles per second", abbreviated cps, until hertz was formally adopted in 1960. Its reach is remarkable for so plain a definition. Mains electricity alternates at 50 or 60 Hz, human hearing starts at roughly 20 Hz, and a monitor advertised at 144 Hz is simply redrawing itself 144 times a second. Anything that repeats can be counted in hertz.

To put both in perspective: a car engine idles at around 800 rpm, while a screen refreshing 60 times a second runs at 60 hertz.

The converter above updates as you type, and the table lists common values for quick reference. Need the opposite direction? Use the Hertz to RPM converter, or browse all Frequency converters.