Photone - Grow Light Meter

In-app purchases
4.6
8.99K reviews
100K+
Downloads
Content rating
PEGI 3
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About this app

Take the guesswork out of plant lighting with Photone, the most accurate plant light meter app. Measure PAR, PPFD, DLI, lux, foot-candles, and color temperature (kelvin) directly with your phone or tablet.

To measure light with research-grade accuracy, Photone uses the most precise sensor in your device: the camera**. Its unique measurement algorithm works directly with the RAW camera sensor data to capture true light intensity. This allows Photone to rival professional handheld PAR meters in accuracy and go even further by helping you interpret the numbers with in-app guides, tools, and additional features.

MEASUREMENTS

⎷ Photosynthetically Active Radiation (PAR) as PPFD in ¡mol/m²/s
⎷ Daily Light Integral (DLI) in mol/m²/d
⎷ Illuminance in lux or foot-candles
⎷ Light color temperature in kelvin
⎷ Extended PAR (ePAR) including far-red light (ePPFD, eDLI) *

FEATURES

⎷ Industry-leading accuracy, comparable to professional PAR quantum sensors
⎷ Pre-calibrated for your specific device **
⎷ No ads
⎷ In-app guides
⎷ Light source selection for every type of grow light (LED, HPS, CMH, etc.) *
⎷ Average and peak readings *
⎷ Plant light calculator
⎷ Hands-free β€œread aloud” function *
⎷ Special underwater measurement mode *
⎷ Custom calibration option to align readings to another meter
⎷ Premium support for advanced grow questions *

* These features require an in-app purchase to fully unlock

DIFFUSER REQUIRED

Like every real light meter, Photone 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/.

** ENHANCED LIGHT MEASUREMENTS WITH THE CAMERA
Accurate light measurements with the camera require a default calibration, which is made available only for selected higher-quality devices. Check the full list of supported devices here: https://lightray.io/diffuser/compatibility/

On devices without default calibration, Photone automatically falls back to the built-in ambient light sensor (ALS). While the ALS works without an external diffuser, it is far less accurate than camera-based measurements. Learn more about the differences between the two sensor types here: https://growlightmeter.com/guides/different-light-intensity-sensors/

UPGRADE OPTIONS

Photone is free to download and use with all basic features without any ads or hidden costs. To unleash its full potential, Photone offers two types of upgrades:
β†’ Lifetime unlocks β€” one-time purchase, always restorable via your Google Account
β†’ Pro subscription β€” full access for as long as you subscribe, cancel anytime

Photone took more than 5 years of R&D to develop. Upgrading not only unlocks powerful features, but also supports future development and keeps 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 β€” so every purchase helps both your plants and the planet.

DOWNLOAD FOR FREE. TRUSTED BY MILLIONS.

Optimized for plant growers and indoor gardeners – whether you’re growing in a grow tent, greenhouse, hydroponics system, an aquarium, or are just looking for the best quantum meter app for your LED grow lights, Photone has got you covered.


Terms and Conditions: https://growlightmeter.com/terms/
Privacy Policy: https://growlightmeter.com/privacy/
Updated on
Sep 19, 2025

Data safety

Safety starts with understanding how developers collect and share your data. Data privacy and security practices may vary based on your use, region, and age. The developer provided this information and may update it over time.
No data shared with third parties
Learn more about how developers declare sharing
This app may collect these data types
App activity, App info and performance, and Device or other IDs
Data is encrypted in transit
You can request that data be deleted

Ratings and reviews

4.6
8.88K reviews
Malcom Wind
October 6, 2025
Too confusing to understand the readings and doesn’t tell you if is shade or full sun just a numberreading that stays wildly in flux. Pop ups to buy a diffuser or to buy premium services prevent you from using the app in any significant way and apparently you have to buy a diffuser to actually get any readings that are accurate so in general a fail from the start.
Did you find this helpful?
Lightray Innovation GmbH
October 6, 2025
Hi Malcom, Thx for the feedback. Yes, Photone may more complicated than other light meter apps, but it is also the only one that is accurate. The accessory is optional, you can simply build a paper diffuser yourself within less than a minute. If you're confused about the readings I suggest starting with our guides and the FAQ 😊 Regards, Dennis
Aslan
September 26, 2025
life saver literally. i was concerned because the model phone I use is supposed to be not a good reader, but I checked with an actual lux /foot lumens digital tool and the numbers where exact as one another, they should allow pictures, I had to leave the 3x3?single plant gorilla cooooooookies!
Did you find this helpful?
Lightray Innovation GmbH
September 25, 2025
Hi Aslan, Wow, thank you for your feedback 🀩 It's very nice of you to go through the trouble of writing a review to share your experience with our community. We highly appreciate it! πŸ™πŸ’Œ I am glad lives were saved by our App, but I really hope you are talking about your plants' lives here 🀞🌱☺️ All the best, Angela and the Photone team
Charles Edmonds
September 22, 2025
I love the Photone app. It's been extremely helpful with getting my lighting dialled in just right. I would be lost without it. Highly recommended. It keeps your ppfd/par and dli on point. No more guesswork.
Did you find this helpful?
Lightray Innovation GmbH
September 22, 2025
Hi Charles, Thank you so much for this kind review 🀩 We highly appreciate that you took the time to share your experience with Photone with our community πŸ’ŒπŸ“£πŸ™ And we are happy that we and our App are helping you and your plants ☺️🌱 All the best, Angela and the Photone team

What’s new

This update adds full camera measurement support for the latest Samsung Galaxy devices (including S25 Ultra, Fold 7, Flip 7, A56, and more). We’ve also improved how screen brightness is handled and made a few other small tweaks to enhance your overall experience.