# Libre Light Sensor — Measure Light in Lux > iPhone app to measure light intensity in Lux using the camera. (iPhone/iPad app by John Harrington.) - Source: https://appshunter.io/ios/app/libre-light-sensor/id1644439968 (this page in markdown: same URL + `.md`) - Developer: [John Harrington](https://appshunter.io/developer/1603002572) - Category: Utilities - Price: Free - Rating: 4.81/5 from 113 App Store ratings · 17 written reviews indexed - Age rating: 4+ - Requires: iOS 16.0 · 1 MB - Languages: English - Released: 2022-09-12 - Data updated: 2026-08-22 - Monetization: free - User reviews in markdown: https://appshunter.io/ios/app/libre-light-sensor/id1644439968/reviews.md ## What is Libre Light Sensor? Measure light levels in any environment. Libre Light Sensor leverages your iPhone's camera to calculate luminosity as measured in Lux. This allows you to determine how much light exposure your eyes are receiving when you wake up, during the day, and before bed in order to optimize your sleep quality. ## Key features - Measure light in Lux - Utilizes iPhone camera - Optimize sleep quality - Track light exposure ## Recent user reviews (10 of 17) All indexed reviews: https://appshunter.io/ios/app/libre-light-sensor/id1644439968/reviews.md ### 5/5 — Great app! *2026-04-18, version 1.2* Great for science projects really helped me, I got a %98. Definitely worth getting! ### 5/5 — Fantastic *2026-03-28, version 1.2* Fantastic app top marks ### 5/5 — Work as good as paid Apps *2026-03-15, version 1.2* Thanks for offering this for free. The reading is same with others that need subscriptions ### 5/5 — Great simple app. A few recommendations *2026-03-13, version 1.2* Thanks for such a great app. It does what it says and that's it! Simple and straightforward. I have two suggestions. As I am using this to check the light from my light therapy box, I'm putting it by my eye, so I can't see the reading on the phone screen. It would be great if I could press a button to save the reading at that moment, so I can pull the phone away from my eye and see the reading. Then press the button again to go back to live measurements. And a button to exit the app would be good too. ### 4/5 — Camera *2025-12-26, version 1.2* The app is working great and it is free! The only problem is that there was no option given for the camera to be in use only when using app. Otherwise, I love its simplicity and that there is a chart for different lux levels in different scenarios. ### 5/5 — Perfect *2025-11-23, version 1.2* Best app I’ve tried to just measure Lux levels. 11.23.25 Today’s it’s not loading. Hope it’s temporary. Seems like an iOS update messed it up ☹️ ### 1/5 — Doesn't Work *2025-11-18, version 1.2* It doesn't work. I downloaded it and there's nothing there to click or work with. Deleted. ### 5/5 — Light resource *2025-11-11, version 1.2* The light was doing, but you have light is faster than sound salt. Light is a very, very very ultra fast. Compared to other light one light, that’s on the lights flicker so much less darkness or lightness, like compared to other lights in the world 🌑🌒🌓🌔🌕🌖🌗🌘🌑 ### 2/5 — This is a toy. *2025-07-27, version 1.2* This light meter tells me that my light therapy light recommended by doctors with a Lux of 10,000 is admitting 35,000-40,000 Lux at 12–14 inches. So it’s just way way off. 2.5 hours after sunrise with a completely blue sky, it’s reading 50,000 lux, which is a “good” estimate with an error variance of ~20,000 Lux. So in other words, it is just a toy. ### 4/5 — Switch camera *2025-07-16, version 1.2* It would be even better if you could add a button to switch between front and back cameras. Just a thought…! ## Frequently asked questions about Libre Light Sensor ### What does Libre Light Sensor do? Libre Light Sensor uses your iPhone's camera to measure ambient light levels and display them in Lux. This helps you understand the intensity of light in your surroundings. ### How can this app help with sleep quality? By measuring light exposure throughout the day and before bed, you can identify and adjust your environment to optimize light conditions for better sleep. Understanding your light exposure can help regulate your body's natural sleep-wake cycle. ### Is Libre Light Sensor free to use? Yes, Libre Light Sensor is a free application. There are no in-app purchases or advertisements mentioned. ### What devices is Libre Light Sensor compatible with? The application leverages the iPhone's camera, indicating it is designed for iOS devices. Specific iOS version compatibility is not detailed but it requires a functioning camera. ### What are common use cases for a light meter app? Common uses include assessing light levels for photography, ensuring adequate lighting for reading or work, monitoring light exposure for health and sleep purposes, and general environmental awareness. ## Version history (last 3 releases) ### 1.2 — 2022-11-25 Upon clicking the information icon to view Lux reference measurements, you may be prompted to rate the app no more than three times in a calendar year. Thanks for using Libre Light Sensor, if you enjoy it (or not), please leave a review. ### 1.1 — 2022-11-23 Upon clicking the information icon to view Lux reference measurements, you may be prompted to rate the app no more than three times in a calendar year. Thanks for using Libre Light Sensor, if you enjoy it (or not), please leave a review. ### 1.0 — 2022-09-12 No release notes. ## Apps similar to Libre Light Sensor | App | Rating | Price | Category | | --- | --- | --- | --- | | [Light Meter LM-3000](https://appshunter.io/ios/app/light-meter-lm-3000/id1554264761) | 4.5 (2,543) | Free | Utilities | | [Light Meter - Brightness Calc](https://appshunter.io/ios/app/light-meter-brightness-calc/id1340670397) | 4.2 (5) | $2.99 | Utilities | | [Light Meter: Lux-525 Pro](https://appshunter.io/ios/app/light-meter-lux-525-pro/id1636117065) | 4.5 (113) | Free | Utilities | | [Lux Light Meter Pro](https://appshunter.io/ios/app/lux-light-meter-pro/id1292598866) | 3.9 (5,115) | Free | Utilities | | [Plant Light Meter: Lux & PPFD](https://appshunter.io/ios/app/plant-light-meter-lux-and-ppfd/id1628111038) | 1.7 (11) | Free | Utilities | | [Lux Light Meter for Mobile](https://appshunter.io/ios/app/lux-light-meter-for-mobile/id1638732220) | 4.5 (229) | Free | Utilities | ## More apps by John Harrington - [Koradi App](https://appshunter.io/ios/app/koradi-app/id1606623606) - [Tip Quick!](https://appshunter.io/ios/app/tip-quick/id1626926148) - [Orange Weather](https://appshunter.io/ios/app/orange-weather/id1628082792) - [List-Maker](https://appshunter.io/ios/app/list-maker/id1631635259) - [Phonetic Trainer](https://appshunter.io/ios/app/phonetic-trainer/id1637123049) All apps by John Harrington: https://appshunter.io/developer/1603002572 ## Related topics [libre light sensor](https://appshunter.io/ios/topics/libre-light-sensor) · [lux meter free](https://appshunter.io/ios/topics/lux-meter-free) · [light sensor](https://appshunter.io/ios/topics/light-sensor) · [lux meter](https://appshunter.io/ios/topics/lux-meter) · [ring sensor](https://appshunter.io/ios/topics/ring-sensor) · [libre 2 plus sensor](https://appshunter.io/ios/topics/libre-2-plus-sensor) · [lux light meter free](https://appshunter.io/ios/topics/lux-light-meter-free) · [imatest spectral sensor](https://appshunter.io/ios/topics/imatest-spectral-sensor) · [sunlight meter](https://appshunter.io/ios/topics/sunlight-meter) · [boston scientific lux](https://appshunter.io/ios/topics/boston-scientific-lux) · [lux light meter](https://appshunter.io/ios/topics/lux-light-meter) · [light measuring app](https://appshunter.io/ios/topics/light-measuring-app) --- *Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-08-22.*