Engine RPM 4+

Acoustic Tachometer

Real-Time Specialties

    • 4.1 • 19 Ratings
    • $8.99

iPhone Screenshots


This app measures the RPM of an engine by analyzing the sound it makes. It uses advanced signal processing algorithms to measure the pitch of the sound and display and log the calculated RPM.

This app will not work if the engine sounds are muffled or unstable or combined with too much other noise. The engine sound must be clear and stable and sound like a single tone. Other sounds can also prevent the engine sound from being analyzed.

The software is configurable for 2-cycle and 4-cycle engines and includes a generic configuration for unusual cases, such as a reduction gear. The normal RPM range is 400 to 90,000 RPM, although much lower RPMs can be measured using the manual RPM matching option.

A detailed manual is available from our support webpage.

What’s New

Version 2.4.1

Fixed a problem with Settings visibility when Dark Mode is used in iOS 13.

Ratings and Reviews

4.1 out of 5
19 Ratings

19 Ratings


Expensive and complicated but it works....

1- Read all the help pages beforehand; it’ll take you about 5-10 minutes but well worth it.
2- I used to set idle on a 2 stroke fuel injected motorcycle where the idle is critical: too high and the bike runs too lean, too low and it bogs down in low RPM starts.
3- At first I had it set up to sample every 3 seconds. That was too long. So I cut to 3/4 of a second and it was less of a hassle. I was able to guesstimate the current RPM’s at 1500, (actual was closer to 1700), so I set up the software that way, kept making small adjustments on idle screw until
I got it just right.
4- Logging the RPMs and times was a nice feature.
5- to get a 5 star price needs to come down materially or ease of use must improve significantly.

Overall I’m happy with this given the alternatives.

blade1693 ,

Pricey but works good.

This was a little more expensive that I would have liked but once I used it I would say it’s defiantly useful. Used it to check low and high speed of my lawnmowers and it’s right on. Just slide around the hint rpm as it’s running and it finds the speed right away. It’s also cool that you can also see the audio waveform. The app doesn’t look to fancy but as long as it keeps working with future iOS updates I’ll be happy.

MichiKyle ,

Got my snowblower working

Was able to dial in my snowblower RPMs no problem. I do think the app should have the cycle/number of cylinders option right on the Home Screen, I think that would help out. Also, would be nice if it had good enough response times to react to transient surges, really it’s only useful for steady RPM values. But overall, did what I needed for much cheaper than a small engine tach.

App Privacy

The developer, Real-Time Specialties, has not provided details about its privacy practices and handling of data to Apple. For more information, see the developer’s privacy policy.

No Details Provided

The developer will be required to provide privacy details when they submit their next app update.


  • Family Sharing

    Up to six family members can use this app with Family Sharing enabled.

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