RPM Meter - Fan Tachometer

RPM Meter turns your phone into a simple sound-based tachometer. Point your phone at a spinning object and the app listens with the microphone, analyzes the sound frequency (FFT), and estimates the rotation speed in RPM (revolutions per minute) in real time. What it does • Real-time RPM reading from the rotation sound your phone hears • Frequency detection with a live spectrum view so you can see the dominant tone • Blades / poles correction: enter the number of fan blades or motor poles for a corrected reading • Session statistics: current, maximum, and average RPM • Hold to freeze the current value, and one-tap reset • Clean, easy-to-read display with light and dark themes Where it helps • Fans and blowers: check the speed of a ceiling, desk, or PC fan • Motors and tools: get a quick rotation-speed estimate for drills, pumps, and small motors • DIY, makers, and hobbyists: a handy field check without a contact tachometer • Learning: a hands-on way to understand frequency and rotation How to use 1) Open the app and tap Start measuring 2) Hold your phone close to the rotating object, in a quiet place 3) If it spins with multiple blades or poles, set "Pulses per revolution" 4) Read the RPM value; tap Hold to freeze it or Reset to clear the statistics Important • This app needs microphone access to listen to the rotation sound. The microphone is used only for measurement — no audio is recorded, stored, or sent anywhere. • Readings depend on the sound and are meant for general reference. Background noise, distance, and the type of rotating object affect accuracy, so values are best used as a guide, not a calibrated laboratory measurement. • Works best with audible, steady rotation in a quiet environment. Privacy • Sound is analyzed only on your device in real time. No audio is uploaded or shared. Supported by banner ads. No account or sign-up required.