Light Meter - Lux & EV Gauge

Turn your iPhone into a professional light meter. Measure illuminance in lux or foot-candles, exposure value (EV), and color temperature (CCT in Kelvin) — all in real time using your camera.

Whether you're a photographer dialing in the perfect exposure, a plant parent ensuring your houseplants get enough light, or a lighting professional checking workspace compliance, this app delivers the readings you need — no expensive hardware required.

REAL-TIME MEASUREMENTS
• Lux and foot-candle readings updated every frame
• Exposure Value (EV) displayed alongside illuminance
• Correlated Color Temperature (CCT) in Kelvin
• Min, max, and average statistics tracked automatically

PROFESSIONAL ANALOG & DIGITAL DISPLAY
• Beautiful analog gauge with animated needle and gradient arc
• Peak reading marker highlights the maximum value on the gauge
• Large digital display with threshold status indicator
• Switch between analog, digital, or combined view

HOLD & THRESHOLD ALERTS
• HOLD button freezes the current reading instantly
• Set a target lux range and get haptic feedback when readings cross your threshold
• Visual indicators show whether you're below, within, or above your target

LIVE GRAPH
• Rolling real-time chart shows light intensity trends
• Spot changes in lighting conditions at a glance

RECORD & SHARE
• Record measurement sessions with one tap
• Sessions save min, max, average lux, duration, and reading count
• Export and share session reports via text — perfect for documentation

CAMERA FEATURES
• Works with front and rear cameras
• Built-in flashlight toggle for additional illumination
• Live camera preview with overlay controls

CALIBRATION & SETTINGS
• Adjustable calibration multiplier for consistent readings
• Customizable analog gauge scale
• Choose your preferred unit: lux or foot-candles
• Keep Screen On option for extended measurements
• Dark-optimized interface for comfortable use

HOW IT WORKS
The app analyzes live video frames using Core Image to compute average scene brightness, then applies an EV-based formula accounting for exposure duration, ISO, and aperture. Color temperature is estimated from RGB chromaticity using McCamy's approximation. A calibration multiplier lets you align readings with a reference meter for improved accuracy.

Note: Smartphone cameras approximate light levels and are not a replacement for certified laboratory instruments. Results are relative and best used for comparison, trending, and general-purpose measurement.

PERFECT FOR
• Photographers adjusting studio or natural lighting
• Plant enthusiasts measuring grow light intensity
• Interior designers evaluating room illumination
• Workplace safety and ergonomic lighting checks
• Educators and students studying optics and photometry
• Anyone curious about the light around them

No ads. No subscriptions. Just a powerful, beautifully designed light meter in your pocket.