Light Meter
Measure ambient brightness in lux using your device's light sensor. Check room brightness, explore photography lighting, or simply see how bright your surroundings are.
Tip: hold your phone where you want to measure and avoid covering the light-sensor area. Readings vary by device and placement.
How to use this light meter
- Open this page in a supported browser on a device with an ambient light sensor.
- Tap Start light meter.
- Hold the device where you want to measure.
- Read the live lux value and move around to compare lighting.
What is lux?
Lux (lx) measures illuminance: how much visible light falls onto a surface. A higher lux number means more light is reaching the measured area.
As a rough guide, a dark room can be below 10 lux, dim interiors may be tens of lux, ordinary indoor spaces can be around 100–500 lux, and bright daylight can reach many thousands of lux. These are broad examples, not strict requirements.
Is my room bright enough?
| Approx. lux | General impression |
|---|---|
| < 10 lx | Very dark |
| 10–50 lx | Dim |
| 50–200 lx | Moderate indoor light |
| 200–500 lx | Bright indoor light |
| 500–2,000 lx | Very bright indoor / near-window |
| 2,000+ lx | Strong daylight or outdoor conditions |
Lighting needs depend on the task, room, surface, time of day, and preference. Use these ranges as a quick reference, not a professional lighting standard.
Using a lux meter for photography
Lux can help you understand how bright a scene is, but it is not the same as a camera exposure meter. A camera exposure reading also depends on ISO, aperture, shutter speed, lens, reflected light, and the camera itself.
For a quick lighting comparison, lux is useful: for example, you can check whether moving a lamp or changing locations makes a scene substantially brighter or darker.
Why doesn't it work?
The Ambient Light Sensor API is not universally supported. A phone can have a physical light sensor used for automatic screen brightness while still not expose its readings to websites.
- Try a recent Chrome browser on Android.
- Use the secure HTTPS version of the site.
- Try different lighting conditions and restart the meter.
- If the page says the API is unsupported, that browser/device combination is not exposing the required sensor.
FAQ
Does this need camera permission?
No. The tool does not use your camera.
Can every Android phone measure lux?
No. Hardware and browser support both matter.
Is the reading professionally accurate?
No. Treat it as a convenient reference and sensor tester, not a calibrated professional light meter. Different devices can report different values.
Does lux tell me the correct camera settings?
No. Lux describes ambient illuminance; it does not directly determine aperture, shutter speed, or ISO.