SoundRPM: Engine Tachometer
Estimate RPM by sound
About
Estimate engine RPM using your iPhone's microphone without any extra hardware. Ideal for classic cars, motorcycles, and small engines, it provides real-time readings with confidence levels and measurement history.
What's New in SoundRPM
1.5
July 29, 2026
fix bugs
Subscription plans
Annual Member
Annual Member
In-App Purchases
$12.99
Lifetime
Lifetime
Developer apps
FAQ
What is SoundRPM?
SoundRPM is a utility app that estimates engine RPM by analyzing the sound captured by your iPhone's microphone. It's designed for stationary engine checks on various types of engines.
Does SoundRPM require any extra hardware?
No, SoundRPM does not require any wires, OBD connections, or additional hardware. It utilizes your iPhone's built-in microphone.
What types of engines can SoundRPM be used with?
SoundRPM is built for classic cars, motorcycles, lawn mowers, generators, chainsaws, and other small engines. It supports both 2-stroke and 4-stroke configurations.
How accurate are the RPM estimates from SoundRPM?
SoundRPM provides estimated RPM readings and includes a confidence level for each measurement. Results can be affected by background noise, phone position, and engine configuration.
Can I save my measurements with SoundRPM?
Yes, SoundRPM allows you to save your measurement history. This feature is unlocked with the optional Lifetime Access purchase.
Is SoundRPM safe to use?
Yes, but with important safety precautions. Do not use SoundRPM while driving and keep your iPhone away from hot surfaces and moving engine parts. It provides estimates and is not a replacement for professional tools.
What are the subscription options for SoundRPM?
SoundRPM offers optional Lifetime Access for unlimited measurements and saved history. Subscription plans are available on a quarterly basis, with automatic renewal unless canceled at least 24 hours in advance.
Does SoundRPM have ads?
No, SoundRPM does not contain advertisements. The app is free to download and use, with optional in-app purchases for enhanced features.