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.