Light Meter LM vs Libre Light Sensor
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
Light Meter LM
Transform your smartphone into a professional light meter. Measure illuminance and color temperature with scientifically validated accuracy, trusted by professionals. Requires a simple diffuser for precise readings.
- Measure illuminance (lux/foot-candle)
- Measure color temperature (Kelvin)
- Industry-leading accuracy
- Pre-calibrated for your device
- Low light sensitivity
- Save peak reading
- Custom calibration option
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Turn your smartphone into a professional-grade light meter. Measure illuminance (lux/foot-candle) and color temperature (CCT in Kelvin) with unmatched accuracy — trusted by photographers, engineers, and lighting professionals worldwide. Why waste money on a hardware meter when you’re already carrying one in your pocket? The LM-3000 offers the same quality and usability as a traditional hardware light meter. Developed by optics scientists at the Zurich University of Applied Sciences, LM-3000 is the only light meter app scientifically validated for accuracy. It achieves professional-grade precision by leveraging your iPhone's front-facing camera sensor with advanced RAW image processing. Unlike relying on estimates like other apps, it adheres to the ISO/CIE 19476 standard, ensuring measurements you can trust for critical applications. MEASUREMENTS ⎷ Illuminance in lux or foot-candles ⎷ Correlated color temperature in kelvin FEATURES ⎷ Industry-leading accuracy, matching professional high-end lux meters ⎷ Pre-calibrated for your specific device ⎷ Excellent low light sensitivity to detect light pollution ⎷ No ads ⎷ No Bluetooth and location permission required ⎷ In-app manual ⎷ Save peak reading ⎷ HOLD function with acoustic signal ⎷ Custom calibration option to align readings to another meter DIFFUSER REQUIRED Like every real light meter, the LM-3000 requires a diffuser to measure accurately. A diffuser scatters incoming light evenly on the sensor and prevents hotspots. While it may sound complex, the solution is surprisingly easy. You have two options: 1) Easily build a diffuser yourself in less than a minute using standard printer paper. This is accurate enough for most use cases. 2) Get the dedicated Diffuser Accessory (free worldwide shipping) for best accuracy and convenience. More details on https://lightray.io/diffuser/ (!) Avoid apps that don’t require a diffuser! They are inaccurate because they ignore the basic physics of light measurement. TRY BEFORE YOU BUY The LM-3000 is free to download and comes with a free trial period. The trial period lasts for two non-consecutive days, giving you enough time to see if the app fits your needs. The status of your free trial will be shown as the "battery level" on the top right of the LM-3000's display and on the "Battery Status" screen. Once your light meter's "battery" is depleted, you may choose a Charging Option to keep using the app. You can pick what works best for you: → Single Charge — top-up for another 48 hours (perfect for occasional use), → Continuous Charging — a monthly subscription (great if you use it regularly), → Unlimited Battery — a one-time purchase for unlimited lifetime access LM-3000 is the result of over five years of dedicated research and development, ensuring you get a tool that is precise and reliable. Every in-app purchase supports future development and helps keep the app ad-free for everyone. As a member of 1% for the Planet, we donate at least one percent of all revenue to environmental non-profits — this is our way of giving back. ACCURACY Accuracy is not an afterthought — Apps developed by Lightray Innovation are developed according to the ISO/CIE 19476 standard. Thanks to RAW image processing and a default calibration per device model they’re able to match the performance of high quality traditional hardware light meters. To ensure quality we rigorously test our apps regularly on upcoming devices. DOWNLOAD FOR FREE. TRUSTED BY MILLIONS. LM-3000 is the go-to light meter for photographers, professionals, engineers, and lighting enthusiasts who rely on accurate measurements — not estimates or guesswork. Download for free today and experience the difference! See the app in action: https://youtu.be/EJW7NfE2qCk Terms and Conditions: https://lightray.io/lightmeter/terms/
Libre Light Sensor
Measure ambient light levels in Lux using your iPhone's camera. Optimize sleep quality by understanding light exposure throughout the day and night.
- Measure light in Lux
- Utilizes iPhone camera
- Optimize sleep quality
- Track light exposure
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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.
Screenshots
Verdict
The clearest difference is review sentiment: Libre Light Sensor at 82% against Light Meter LM's 40%. Libre Light Sensor also leads on in-app purchases (none vs 3) and rating (4.8 vs 4.5). Light Meter LM's advantage is ratings volume (2.6K vs 113) and device support (3 vs 1). On price, update cadence, ads and iOS requirement there is nothing between them.
Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS
Both are free to download. Light Meter LM sells 3 in-app purchases, starting at $3.49 per month. Libre Light Sensor asks for nothing beyond the download.
Libre Light Sensor holds the better App Store score, 4.8 against 4.5. That said, the two scores are not equally well evidenced: Light Meter LM has 2.6K ratings behind it against 113, so its average is the more settled of the two. Written reviews point the same way: 40% of Light Meter LM's written reviews are positive against 82% of Libre Light Sensor's.
Light Meter LM ships an update monthly, Libre Light Sensor every 5 weeks. The most recent releases landed on September 23, 2026 and September 22, 2026 respectively.
| Parameter | Light Meter LM | Libre Light Sensor |
|---|---|---|
| Price | Free | Free |
| Rating | 4.5 (2.6K ratings) | 4.8 (113 ratings) — better |
| Positive reviews | 40.3% of reviews | 82.4% of reviews — better |
| Number of ratings | 2.6K — better | 113 |
| Update frequency | Monthly — better | Every 5 weeks |
| Ads | No | No |
| In-app purchases | Yes | No — better |
| Monetization | Free with in-app purchases | Free — better |
| Devices | iPhone, iPad, iPod — better | iPhone |
| Requires iOS | 15.0 — better | 16.0 |
| Further details — not scored | ||
| Size | 22 MB | 1 MB |
| Age rating | 4+ | 4+ |
| Developer | Lightray Innovation GmbH | John Harrington |
Customer experience
Light Meter LM
Libre Light Sensor
Bugs and requests
Light Meter LM
Reported bugs
3 issues- Diffuser not recognized even when used
- App locks up/crashes
- Constant diffuser pop-up interruptions
Requested features
3 requests- Ability to use rear camera
- More flexible diffuser options
- Improved accuracy without diffuser
Libre Light Sensor
Not enough reviews yet to summarise bugs or requests.
In-app purchases
Light Meter LM
- Continuous Charging$3.491 Month
- Single Charge$0.99
- Unlimited Battery$19.99
Libre Light Sensor
No in-app purchases
Questions
Is Light Meter LM free?
Is Libre Light Sensor free?
Which has better reviews, Light Meter LM or Libre Light Sensor?
Do Light Meter LM or Libre Light Sensor have ads?
Which is updated more often, Light Meter LM or Libre Light Sensor?
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