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.