RPM Stroboscope is a simple stroboscope app that aids in determining the speed of rotating objects or the frequency of vibrating objects.


There are two modes that can be used, this is indicated by the label above the text field. When the label displays RPM, the value in the text field below displays the value in revolutions per second and the light flashes corresponding to that value. When shining the flashing light at a shaft that is spinning, it will appear to be stationary if the speed is the same as the value indicated.

Similarly, when in hertz mode the label will display Hz instead of RPM. In this case the value in the text field is converted to Hz and the light flashes corresponding to this value.

To switch between modes simply tap on the label. When in either mode, if you want to verify shaft speed or vibration frequency, you can tap on the text field and enter the value you want to verify.

If the speed or frequency is unknown, you can use the plus and minus buttons on either side of the text field to increment the value in order to find the speed or frequency. Long pressing on the plus or minus buttons will increment the value by 10 when in RPM mode and by 2 when in Hz mode.

If you double tap in an open area the plus and minus buttons will change to multiply and divide buttons. Tapping these will multiply by 2 and divide by 2. Long pressing the buttons will continue to increment by 2.

For best results, the shaft needs a unique feature so you can tell if the shaft appears stationary. If the shaft does not have a unique feature, referred to as a timing mark, you could simply mark the shaft when it is not spinning, that acts as the needed feature.

-External Flash

A Nova external flash can be connected through bluetooth for additional functionality.

For more information about the Nova flash visit

What’s New

Version 1.3.1

Fixes problem that would prevent light from flashing

Ratings and Reviews

3.5 out of 5
2 Ratings

2 Ratings

Birdy949 ,

Good, look forward to better

Just installed 2 ceiling fans. One noticeable slower. Taped a small piece of paper to one blade and used app to test and compare both units. Worked great. Takes awhile to hunt for speed but hey, you cannot knock free. I was able to get the fan company to send replacement parts for the defective fan. The app could use more instructions especially for those who have no clue how to work a timing light. Good job overall.

thehotrodguy ,

Worked well

I used this application to help resolve a problem that i was having with a pool pump. I needed to be able to verify the shaft seed, i did a app search and found this app. The instructions are a bit poor but if you know how strobes work you can get it to work just fine. For this app to work you will need to mark the shaft with a reference mark. I painted a white dot on the shaft, start the app and adjust the speed up or down until the dot stops rotating. When the dot stops moving you have matched the RPM’s for the shaft which should be equal to the motor speed.

Ursus9212 ,


You shine the strobe from your flash onto a rotating item. You adjust the RPM value until the item APEARS still. Then read what you put in and you have an approx. value. Simple!! Awesome!!
I needed it for my toy steam engine!

App Privacy

The developer, Cody Huber, 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

    With Family Sharing set up, up to six family members can use this app.

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