Lux Light Meter

Lux Light Meter turns your phone's ambient light sensor into a simple, honest illuminance meter. Point the top of the phone at the light, read the value, and compare it with recommended levels for reading, working, studying or photography.

WHAT IT DOES
• Live reading in lux or foot-candles, on a log-scale dial that fits moonlight and direct sun on one scale
• EV100 (exposure value at ISO 100) for photographers
• Min / average / max for the current measurement, with a running timer
• Light-level bands at a glance: night, twilight, dim, living room, office, bright indoor, precision work, daylight, direct sun
• The three closest reference levels, so "is this enough light for reading?" is answered on the spot

SAVE AND COMPARE
• Save readings with a label (desk, kitchen, nursery…)
• Delete with undo, edit labels, export everything as CSV or share as text
• Each saved reading keeps the raw sensor value and the calibration in force, so an export can be rechecked in a spreadsheet

REFERENCE TABLE
Recommended maintained illuminance for homes, offices, classrooms, shops, healthcare and industry, following the task tables of EN 12464-1 as they are commonly quoted, plus typical outdoor levels from full moon to direct sunlight. The row nearest your live reading is highlighted.

CALIBRATION
Phone light sensors are built for screen brightness, not metrology, and can differ from a reference meter by a factor of two or more. Point both at the same light, type in the reference meter's reading, and the app derives a correction factor for your phone. One tap resets it.

HONEST ABOUT ITS LIMITS
• Shows your sensor's range and resolution, and warns when the sensor is saturated
• Explains itself on devices without a light sensor instead of showing a frozen dial
• Keeps the screen awake while measuring (can be turned off)
• 15 languages, light and dark theme, follows your system

PRIVACY
Readings stay on your device. Nothing you measure is uploaded. No accounts, no sign-in.

SOURCES
Indoor values follow EN 12464-1 (Light and lighting — Lighting of work places — Part 1: Indoor work places), published by CEN: https://www.cencenelec.eu/ — editions differ in places, and a lighting design works from the standard itself. Outdoor values are typical measured levels. Lux Light Meter is not a certified measuring instrument and is not affiliated with CEN or any standards body.