Convert RPM to Kilohertz

About converting RPM to Kilohertz

RPM (rpm) and Kilohertz (kHz) are both units of frequency, so converting between them is a single multiplication: multiply your RPM figure by 0.00001667. Ten RPM comes to 0.0001667 Kilohertz, and a hundred works out at 0.001667 Kilohertz.

Rule of thumb: going from RPM to Kilohertz divides, so the figure always shrinks — it takes about 60,000 RPM to make a single Kilohertz. 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 Kilohertz?

The kilohertz is the range of sound and of the oldest broadcast radio. The top of human hearing sits somewhere near 20 kHz in a young ear, and digital audio is sampled in kilohertz — CD audio at 44.1 kHz, most video and studio work at 48 kHz or above — because a sample rate has to comfortably exceed the highest frequency you want to capture. AM radio is the other kilohertz territory: the numbers on an AM dial are station frequencies in kilohertz, which is why they run to three or four digits while the FM dial beside them shows tidy two-digit megahertz.

To put both in perspective: a car engine idles at around 800 rpm, while AM radio stations sit around 1,000 kilohertz on the dial.

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