Photone - Grow Light Meter

In-app purchases
4.7
8.11K 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
Apr 16, 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

4.7
8.01K reviews
R J
June 15, 2022
I'm using Nokia 8.3 Android 12 which needs calibration the app tells me. A way out until calibrated under day LED,the readings are close to lux meter accuracy. 5* for ease of use finding best areas for light and with the calculator,best intensity and hours for growth stages. Edit: After many uses I thought I would add the advanced average feature is bang on. Can't recommend enough. Donation on amount used forthcoming! 👍
9 people found this review helpful
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Lightray Innovation GmbH
June 5, 2022
Hi Brad, Thank you very much for your detailed feedback! Happy to hear that our app works well for you and you found everything that you need :) Best regards, Dominik and the Photone Team
Michael Sinclair
April 9, 2023
Better than the seneye for reef aquaria. I was using the seneye for PAR readings and it was giving me 100 to 150 in an area where my mushroom corals were trumpeting (indicating too low light levels, usually less than 50) however when I used this app it gave me readings 30 to 70 which was more accurate. I then moved the corals into a 120-150 PAR region and they have responded well. On top of that my seneye stopped working and the seneye customer service were very unhelpful.
3 people found this review helpful
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Lightray Innovation GmbH
April 15, 2023
Hi Michael, Thank you very much for your insightful review! Happy to hear that our app is helpful to you :) Happy reefing! Best, Dominik and the Photone Team
moo kau
April 21, 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
April 21, 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

What’s new

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