MyRPMCalc
Engine RPM From Sound
Only for iPhone
$1.99 · Designed for iPhone. Not verified for macOS.
iPhone
No sensors, no wiring, no app switching. Point your phone's mic at the engine and read live RPM for any cylinder count, 2-stroke or 4-stroke.
Point your phone at a running engine and read its RPM instantly — no OBD adapter, no clip-on inductive sensor, no wiring. RPMCalc listens through your microphone and calculates engine speed straight from the sound of the exhaust or the engine itself.
HOW IT WORKS
Every engine's exhaust note has a fundamental firing frequency set by its cylinder count, stroke cycle, and RPM. RPMCalc analyzes that frequency in real time and converts it to a live RPM reading — accurate to the nearest 1 RPM on the digital readout, with a classic analog tachometer dial for an at-a-glance feel.
BUILT FOR ANY ENGINE
- Set any cylinder count from 1 to 12
- Choose 2-stroke or 4-stroke cycle
- Works on cars, motorcycles, lawn mowers, generators, chainsaws, go-karts, boats, and other small engines
WORK ALONE, HANDS-FREE
Diagnosing an engine is usually a two-person job — one to rev it, one to watch the gauge. RPMCalc's Auto-Freeze feature fixes that. Set a delay (5 to 30 seconds), tap Start Listening, prop the phone near the exhaust, and walk to the driver's seat. RPMCalc automatically freezes the reading after your chosen delay so it's waiting for you, unchanged, when you walk back. A manual Freeze/Resume button is also there any time you want to hold a reading on the spot.
SIMPLE, FOCUSED, NO CLUTTER
One screen. No accounts, no ads, no subscriptions, no clutter. Just a tachometer, a couple of settings, and a listen button.
PRIVACY
RPMCalc processes audio entirely on your device. Nothing is recorded, uploaded, or shared.
PLEASE NOTE
RPMCalc estimates engine speed acoustically and is not a certified or calibrated tachometer. Background noise, wind, and exhaust modifications can affect accuracy. Don't rely on it as the sole basis for safety-critical decisions like redline limits or tuning — always follow your engine or equipment manufacturer's official guidance.
Ratings & Reviews
- This app hasn’t received enough ratings or reviews to display an overview.
The developer, C&S Industries, LLC, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy .
Data Not Collected
The developer does not collect any data from this app.
Accessibility
The developer has not yet indicated which accessibility features this app supports. Learn More
Information
- Seller
- C&S Industries, LLC
- Size
- 3.5 MB
- Category
- Productivity
- Compatibility
Requires iOS 17.0 or later.
- iPhone
Requires iOS 17.0 or later. - Mac
Requires macOS 14.0 or later and a Mac with Apple M1 chip or later. - Apple Vision
Requires visionOS 1.0 or later.
- iPhone
- Languages
- English
- Age Rating
4+
- 4+
- Copyright
- © 2026 C&S Industries, LLC
