Lux Meter – Light Meter

Lux Meter turns your iPhone into a professional light meter. Using the camera and the ISO 2720 photographic standard, it measures illuminance in lux and foot-candles in real time. Whether you're setting up studio lighting, checking your desk for eye comfort, dialing in grow lights for your plants or metering a film scene, Lux Meter gives you the numbers the pros rely on. MEASURE • Real-time lux and foot-candle readout with a one-tap unit switch • Exposure Value (EV) and color temperature (CCT in Kelvin) • Spot metering on a reticle in the middle of the camera view, or average metering of the whole frame • Live histogram, min / max / average and a live chart • A/B compare: pin a reading as the reference and see the difference in EV and percent • Lock a reading, and a low-light path that reads below 1 lux ROOM SURVEY (Premium) • Measure a grid of points across a room and see it as a heat map • Average, minimum, maximum and uniformity (U₀), checked against workplace targets for offices, classrooms, workshops, retail and corridors, or your own target • Share the result as a PDF report EXPOSURE CALCULATOR • Set two of aperture, shutter and ISO — it solves the third • ND filter, exposure compensation and a Sunny 16 helper • Cinema mode with frame rate, shutter angle and the 180° rule, plus a depth-of-field calculator (Premium) GROW LIGHT (Premium) • Turn a reading into PPFD and Daily Light Integral (DLI) for sunlight, LED, HPS, metal-halide or fluorescent light • Photoperiod setting and a light guide for low- to high-light plants TARGETS & FEEDBACK • Presets for reading, office, photography, film, plants and aquariums • Target band with an in-range indicator • Optional haptic and audio meter tick that speeds up as the light gets brighter CALIBRATION • Separate calibration for the front and back cameras, with raw and calibrated values side by side • Manual multiplier, plus multi-point calibration across the whole range (Premium) HISTORY & REPORTS • Save single readings or record the light over time, with notes and an optional location tag • Chart and statistics for every recording • PDF reports and CSV export (Premium) LUX METER PREMIUM A one-time purchase, no subscription. Unlocks Room Survey, PDF reports, unlimited history and recording time, CSV export, multi-point calibration, Grow Light, cinema mode and depth of field. MORE • 11 languages with instant in-app switching • Dark design with a light mode, grid overlay, brightness pin and keep-awake 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 the best results, calibrate once against a reference meter. Measure light like a pro. Download Lux Meter.