Lux Light Meter · Photometer
Lux · EV · Modes · History
Only for iPhone
Free · Designed for iPhone. Not verified for macOS.
iPhone
Now estimates PPFD and DLI for grow lights — pick your light source and photoperiod and see whether a shelf really hits your plants' daily target.
Measure light properly — in lux, foot-candles, EV, or PPFD for plants — using your iPhone's camera to read the light falling on the scene.
GROW LIGHTS & PLANTS
• PPFD estimated from your live reading, matched to your light source: white LED, HPS, fluorescent or daylight
• DLI for a 12, 14, 16 or 18 hour photoperiod, so you can tell whether a shelf actually reaches a seedling's daily light target
• These are spectrum-based estimates, not a calibrated PAR sensor. Read them as guidance for placing lights, not as lab data.
FOUR MEASURING MODES
• Auto — radial gauge with the closest real-world reference shown live
• Outdoor — a log scale to 100,000 lx, from deep twilight through overcast and direct sun
• Indoor — 10 to 10,000 lx, from corridor and living room up to reading desk, drafting and surgical levels
• Photo — EV at ISO 100 with a suggested shutter speed
HISTORY THAT ADDS UP
• Every reading saves automatically, with a 7-day trend chart and plain-language insight such as "+12% vs your 7-day average"
• Notes and favourites — label a reading "kitchen window 3pm" and star it
• Compare any two saved readings side by side
• Export everything as CSV, or share a single reading as an image
MEASUREMENT DETAIL
• Kalman-smoothed readings, so there is no jitter to read through
• Min, max and average with elapsed time
• Log-scale range bar in Outdoor and Indoor modes
• Lux, foot-candle and EV units
• Calibration factor — scale every reading by a multiplier to match a reference meter you trust
WHO USES IT
Indoor gardeners and grow-tent owners · photographers and filmmakers · electricians and lighting installers · studio engineers · workplace and office ergonomics checks · industrial lighting surveys
HOW IT WORKS
Readings are estimated from the back camera's exposure, so this is a reflected-light measurement: point the back of the phone at the surface you care about and keep the lens clean and unshaded. Because it reads reflected light, a white wall and a dark carpet under identical lighting will not read the same, and very dim scenes are the least reliable. Cameras differ between models, so for absolute numbers set the calibration factor against a meter you trust.
Available in 25 languages.
Ratings & Reviews
- This app has not received enough ratings or reviews to display an overview.
New Room Survey: measure several spots in one pass and get the average, a per-spot verdict against your chosen lighting standard, and the uniformity score used in lighting practice. The opening screen also no longer stalls when the network is slow.
Thanks for the reviews and feedback!
The developer, Kyu-Hee Jang, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy .
Data Used to Track You
The following data may be used to track you across apps and websites owned by other companies:
- Identifiers
- Usage Data
Data Not Linked to You
The following data may be collected but it is not linked to your identity:
- Identifiers
- Usage Data
- Diagnostics
Accessibility
The developer has not yet indicated which accessibility features this app supports. Learn More
Information
- Provider
- Kyu-Hee Jang
- Size
- 58.8 MB
- Category
- Utilities
- Compatibility
Requires iOS 16.4 or later.
- iPhone
Requires iOS 16.4 or later. - Mac
Requires macOS 12.0 or later and a Mac with Apple M1 chip or later. - Apple Vision
Requires visionOS 1.0 or later.
- iPhone
- Languages
- English
- Age Rating
18+
- 18+
- Contains
Advertising
- Copyright
- © Copyright 2026 Simon Jang. All rights reserved.