RPM Meter – Engine & Fan RPM

RPM Meter turns your phone into a contactless tachometer. Point the microphone at a running fan, engine, or spindle and get a steady RPM reading in seconds. No wires, no reflective tape, no extra hardware.

HOW IT WORKS
The mic hears your machine's tone. An FFT finds the dominant frequency, and a per-machine profile converts Hz to RPM: fan blades, engine strokes and cylinders, or direct one-event-per-rev spindles.

BUILT FOR REAL MEASUREMENTS
• Fan profile: 2 to 9 blades
• Engine: 2-stroke and 4-stroke, 1 to 8 cylinders
• Direct: hard-drive spindles and one event per rev
• Custom: 0.5 to 16 events per revolution
• Harmonic checks (f/2, f/3) so a harmonic never reads 2x or 3x too high
• Peak-to-floor discrimination: the tone must rise out of the noise floor
• Live spectrum with a marker on the detected tone
• MIN, MAX and AVG session stats; Hold freezes the reading

PRIVATE BY DESIGN
Audio is analyzed on your device only. Nothing is recorded, stored, or sent.

Try it on a case fan, a ceiling fan, a drill press, a motorcycle, a mower, or a hard drive. If it hums a steady pitch, RPM Meter can read it.