Libre Light Sensor 4+

All other lux meters I installed and uninstalled, with their many positive reviews, started free, then sometimes it was very obviously inaccurate. Eventually it would boil down to “it would be accurate if you buy this or that and add it on top … now you could make one yourself from newspaper, but it will not be as accurate”!!
I used this to measure how much light will hit my eyes when I read a book, vs read from browser on monitor, vs read dark theme article on monitor. It gave me perfect comparison of each for free. Reduce monitor brightness and contrast, all show how much difference they make.

I tried another App and it basically did NOTHING but forcing you to pay for a subscription. So I found this one and I am blown away. This works great. You point it a the light source and it tells you how much lux your plants are getting. Now I know why they aren’t doing as good as they should. I’m like a 71 year old kid running around pointing my phone at every thing. I would gladly pay for this; not a subscription, but a one time fee of $5-$8.

This app is very simple and fun to use - point your phone to something and see illuminance value of what the camera sees. Seems to be reasonably accurate compared to expected values of Lux. Handy reference scale is provided in app. No ads so far. Thank you developer for nice work.
I needed something like this for a very specific task. I restored the headlight lenses on my old car and wanted to see how much more light I get after refinishing the surface of plastic.