Lux Meter – Light Meter

Turn your iPhone into a pro light meter. Measure lux, foot-candles, EV and color temperature in real time — calibrated, fully offline, no ads.

Lux Meter turns your iPhone into a professional light meter. Using your camera and the ISO 2720 photographic standard, it measures illuminance in lux and foot-candles in real time — accurately, fully offline, with no ads and no sign-up.

Whether you're setting up studio lighting, checking your desk for eye comfort, dialing in grow lights for plants, or metering a film scene, Lux Meter gives you the numbers the pros rely on.

MEASURE • Real-time lux and foot-candle readout (tap to switch units) • Exposure Value (EV) at your chosen ISO • Color temperature (CCT in Kelvin) estimate from the camera • Live camera preview with a center spot reticle • Spot metering (center) or average metering (whole frame) • Min / max / average statistics with a live chart • Hold to lock a reading • Plain-language light labels (Office lighting, Overcast day, Direct sunlight…) • Low-light path reads down to sub-1 lux

EXPOSURE CALCULATOR (2-in-1) • Set any two of aperture / shutter / ISO — it solves the third • Cinema mode: frame-rate and shutter-angle presets, plus the 180° rule • ND filter and exposure compensation • Sunny 16 helper and a depth-of-field estimate

TARGETS & PRESETS • Use-case presets: Reading, Office/Ergonomics, Photography, Film/Video, Plants & Greenhouse, Aquarium/Terrarium • Set a target lux band and get a subtle alert when the light is in range • Optional haptic and audio meter tick that speeds up as light increases

CALIBRATION YOU CAN TRUST • Independent calibration for front and back cameras • Multi-point calibration fitted across the whole range • See raw and calibrated values side by side • Reset to default anytime

SAVE & EXPORT • Save single readings or record a session over time • Min/max/average per session, notes and optional location tag • History list with rename, delete and CSV export (share sheet)

BUILT RIGHT • Works 100% offline — no account, no tracking, no network • No ads, nothing locked behind a paywall • Grid and histogram overlays, screen-brightness pin, keep-awake • Clean dark-first design, light mode too • 8 languages with instant in-app switching

A note on accuracy: iOS does not give apps access to the ambient light sensor, so Lux Meter uses camera-based reflective metering (ISO 2720). For best results, calibrate once against a reference and use the same lighting conditions.

Measure light like a pro. Download Lux Meter.