Photone - Grow Light Meter

In-app purchases
4.8
8.12K reviews
100K+
Downloads
Content rating
PEGI 3
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About this app

Take the guesswork out of grow lighting! Measure PAR / PPFD, Lux, fc, and Kelvin: All within the most accurate light meter app out there.

Setting up your plants' optimal lighting is not easy — if not impossible without a proper PAR / PPFD plant light meter. Calculating your indoor garden's daily light integral (DLI) to match your plants’ needs allows you to optimize your lighting for maximal yield at minimal electricity consumption.

Our Photone grow light meter app measures photosynthetically active radiation (PAR) as PPFD in µmol/m²/s, calculates the daily light integral (DLI) in mol/m²/d, and measures illuminance in foot candles or Lux. It also allows you to measure light temperature in Kelvin which can help you determine if a light is suitable for fruiting and flowering or for vegetative growth.

It is by far the most accurate light meter app for plants and achieves industrial grade accuracy that easily compares to dedicated and expensive quantum PAR meters for many hundreds of dollars. You can learn more on how we achieve over 95% of accuracy against research grade laboratory equipment and how to achieve maximum accuracy by yourself in our white paper: https://growlightmeter.com/whitepaper/

The app also contains useful guiding articles to help you get the most out of your plant lighting. In addition, you can find more informative and educational content on our blog: https://growlightmeter.com/blog/

Wondering how much light your plants need? The plant lighting calculator on our website helps you to dial in your lighting to your specific plants' needs: https://growlightmeter.com/calculator/

To receive an accurate PAR and thus DLI measurement, you need to select the correct light source that you are measuring.
Updated on
16 Apr 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

4.8
8.02K reviews
moo kau
21 April 2025
I've been using it on and off since beta. Now I see there are "pro" settings they want me to pay $75 to unlock. They also want to sell a diffuser for $40. Oh, but it's "on sale" for an "introducotry" price of $26, except it was introduced years ago. $100+ for a setup that uses my own phone hardware to extrapolate. It's a good tool, but if I want to "go pro," I'll save up the 5x for a pay once, dedicated hardware meter.
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Lightray Innovation GmbH
21 April 2025
Thanks for sticking with us since the Beta! Your feedback is appreciated 🙏 I’m briefly addressing the points you’ve mentioned: As Beta user you don’t lose any features if you don't reinstall the app 👌 Buying the diffuser accessory is optional. With Photone Pro you’ll constantly get more new features a hardware meter can never match 💪 Angela
Joey Farley
18 January 2025
This app has been fantastic, I have the diffuser accessory now, and it made it a lot more stable. I have been using paper and it was reading quite a bit lower than it actually was and I always thought I was having to run my plants with low light and I felt bad always trying to push them thinking I was running low. Now, with the accessory, it seems to be much better. I had to raise my lights and dim one of them, and after a couple of weeks, everything is great.
10 people found this review helpful
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Lightray Innovation GmbH
18 January 2025
Hi Joey, 🤩 Wow, thank you so much for this review and for taking the time to share your insights and experiences with our app and our diffuser and cosine corrector accessory with the community!🙏 It's really cool to hear that we contribute to the well-being of your plants and your satisfaction with light measuring ☺️ Kind regards, Angela & team
A Google user
21 April 2025
I've been using the app and checking it out after using a lux meter and doing the math for PPFD. i like it. it appears to work quite well for me. it is repeatable. i like that. Points to a good working app.
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Lightray Innovation GmbH
22 April 2025
Hi there, Thank you very much for your feedback 🙏 We highly appreciate you taking the time to share your insights in Photone with our community 📣💌 It also keeps us motivated to do our best work 💪 All the best, Angela and the Photone team

What's new

This update fixes the accessory placement help for various screen resolutions among other minor bugfixes.