LUX - Light Meter
An iOS app that measures ambient brightness in lux using the camera. Open it and start measuring right away.
Inside the app
Select an image to view it full size
What you can do
- Measure as soon as you open the app — Read brightness in lux or foot-candles, and hold a reading.
- Track changes in light — See the minimum, average, and maximum lux of a session, along with color temperature (CCT / Kelvin).
- Save and use your readings — LUX Pro adds measurement history, CSV export, and PPFD for plant lighting.
Readings are approximate values calculated from the iPhone camera. They are not guaranteed to match the accuracy of a dedicated light meter.
Measurement data is processed on your device and is not sent to external services. For information used by advertising, usage analytics, and purchase management services, see the Privacy Policy.
Story
I keep houseplants at home, and when deciding where to put them I wanted to know whether a spot actually got enough light. Before buying a dedicated light meter, I looked for an app that could measure it with my phone.
The ones I found were packed with features but never ready to measure the moment I opened them. I had to hunt for the right button, and no matter how often I used them the steps never stuck. It felt like this could be simpler. Building it myself was an option, so I did.
There was no grand problem behind it. I wanted a light meter I found easy to use. That was the reason.
The first thing I decided was that it had to be measuring the instant it opened. The initial release did nothing but read illuminance. Features have been added since, and that one point has not changed.
After launch, an in-app survey collected 175 responses. Plants were the most common use, same as mine — but people were also checking reading light, running school science projects, setting up party lighting, teaching classes, and working in healthcare and elder care. Uses I never imagined when I built it, taught to me afterward.