Light Meter - Lux & EV Gauge
Vladislav Zhirnov
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.