Lux Meter (Light Meter)

Seems to work well. It's very easy to use. I haven't checked it against a professional meter, but it's relatively close based on my experience. It does have a calibration factor that can be adjusted to match a calibrated light meter. For those who think it is using the wrong side of the phone to measure, you need to look up the difference between incident and reflected light meters. Incident measures the actual light strength. Reflected measures the light after is is reflected off an object.

I checked its accuracy against an industry standard luxmeter (Gigahertz Optic) and my phone was within 4% of these values except for near zero lux values where it was within 25% but I'm not worried about that, few would sweat over 1 lux difference at 3 lux! Would be nice to change the graph time or export/save/hold measurements. Otherwise its a great app (sans Ads)! Four stars!