Is the Flicker tester app accurate?

I been watching some flashlight reviews on YouTube and notice that David Sunshine test the flicker of the flashlight’s.

I been reading many reviews here but never seen you guys test the flicker.

I think it gives some good information about how the driver performs and if the flashlight is going to give you headache or tired eyes if it flickers (that’s what I have been reading here about noticeable pwm).

Just think it’s a good app to have checking your flashlights for reviews or to test new drivers.

The app is available for android and iPhone but I didn’t get it to work on my android phone (just said “not enough light”) but on my wife’s iPhone 6 it works great. (She is probably going to get crazy when I borrow her phone alot now)

To get the screenshot over to my phone I just press save and click on Facebook messenger and send it to me and I got it.

Search for “Flicker tester” at app store.

Link to official page with some info how the calculate stuff and so on:


Check this video at 9:00 and he explains alittle bit about it.



The question is: is it accurate straight from the app store or do I need to calibrate it?

I think the calibration only apply for the Hz and not the flicker index or the flicker % since those numbers are calculated from one cycle.

From the figure: Percent flicker = 100 x (A – B)/(A + B)

Flicker index = Area 1/Area 1 + Area 2

Edit: it seems they have fixed the app for android phones now.

Seems it only works for iPhone (I think) and the app must be pretty much calibrated from the start (I hope) since there is not many iPhone models (Vs android) and the components is known of those phones.

To calibrate the frequency I must put the phone’s camera on a light (I must know at what frequency that lamp flickers) and type in the know flicker frequency.

But how to do that easiest?


An old fluorescent tube should do about 100Hz, twice the speed of the electric grid in Europe

thanks for the info about this app
I put it on my iPhone 8

my results were very inconsistent until I put paper over the camera, Im still learning

I tested a PT-18, which is known to have no PWM

here are some of the results from the app:

without the paper over the camera it looked like this:


here are a couple photos of the incandescent light in the bathroom:

the result are still pretty variable…

I expected to see Zero Flicker on the NoPWM flashlight and Incandescent House lights… not sure why the app thinks they flicker…

meanwhile if you want to see a List of Lights that Use PWM, click here

here is how I find flicker, using my phone camera

My understanding is that incandescent bulbs flicker because they have 60 Hz AC power being pulsed through them. (Or 50Hz if you live in EU I think)

There are two types of flickering with lights – visible flicker and invisible flicker.

Check this slow motion video of a light bulb.

yes I agree house power is at 60hz, in California
note that the two scans I posted of incandescent are reporting 100Hz and 91Hz… not consistent

if you look closely at the first two flashlight scans, although they are consistent in Hz, they are inconsistent in % flicker

the app seems to be quite sensitive, and so far I have not been able to reproduce two consecutive identical readings…

Im open to learning to improve my technique.
So far, I don’t think that the app is providing accurate info from which to determine whether a flashlight is using PWM, but if you want to learn how to detect PWM with your phone, watch the video I posted.

that technique also detects Constant Current flicker… which is much harder to detect than PWM

If anyone it’s interested in this app for android it seems to work now.
Atleast on my android phone.

do some tests on actual lights you own
let us know if you get consistent repeatable results that make sense

I still cannot use the app, it is inconsistent, and the results make nonsense