Acoustic Tachometer

Acoustic Tachometer estimates engine RPM from exhaust or engine sound using your iPhone microphone. Choose an engine profile, start listening, and watch the app lock onto the dominant firing frequency. The app reports RPM, confidence, harmonic support, and candidate frequencies so you can tune idle speed, compare engine behavior, and capture repeatable measurements without attaching hardware. Built for quick checks on cars, motorcycles, small engines, and rotary engines where a contact tachometer is inconvenient.