Kilohertz to RPM

About Kilohertz and RPM

Kilohertz (kHz): A thousand hertz; the unit for AM radio frequencies and low-frequency audio. Common uses: AM radio (530-1700 kHz), keyboard scan rates, and the upper end of human audible frequencies.

RPM (RPM): Revolutions per minute; a practical unit for rotating machinery, equal to 1/60 Hz when reinterpreted as cycles per second. Common uses: Engine speed (idle ≈ 600-800 RPM, redline 6,000-8,000 RPM in cars), hard drive speeds (5,400 or 7,200 RPM), kitchen mixers, and turntable speeds (33⅓ or 45 RPM).

How the conversion works

Frequency uses the SI hertz (Hz, cycles per second). 1 kHz = 1,000 Hz; 1 MHz = 1 million Hz; 1 GHz = 1 billion Hz. RPM and BPM are both "cycles per minute": 60 RPM = 1 Hz.

The exact relationship is RPM = kilohertz × 60000, which the calculator at the top of this page applies in both directions. Type into either field and the other updates immediately.

When this conversion matters

Converting between kilohertz and RPM comes up wherever frequency measurements move between systems — from one country's conventions to another's, from a scientific reference to a practical specification, or from one industry's working unit to another's. The calculator and reference table above cover the everyday range; for unusual values you can type any number into either field.