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Keep The Guesswork Out of Grow Lighting

Measure PAR / PPFD, Lux, Kelvin:
All with an app

Grow Light Meter App

The revolutionary
Light Meter App
you can trust

Photone - Grow Light Meter

Go Pro:

Set up your plants’ lighting with a proper PAR light meter.

Photone (previously named Korona) is the light meter app that allows you to take all the light measurements relevant for your plants and for all widely used grow light technologies.


  • PAR / PPFD in µmol/m²s

  • Illuminance in Lux and foot-candle

  • Light temperature in Kelvin

Your Benefits

Built for Grow Lights

We actively develop, test, and optimize for the widely used grow lights in the market.

No Costly Equipment

Photone only requires your smartphone’s camera — nothing else.

Tailored to Plants

Measure PAR in µmol/m²s and even calculate your plant’s DLI at the palm of your hand.

Proven Accuracy

Compared to various common hardware light meters, Photone is repeatedly achieving the lowest average error rates in measuring grow light illuminance.

Average Error

31.7 %
Light Meters
5.1 %
iPhone X


4.7 %
iPhone 7
4.2 %
iPad Pro

More information regarding measurement and evaluation details on the above error rates can be found in our white paper.

White Paper

What Our Users Think

out of 5
vitvorg, Jan 21, 2020
Useful and user friendly with a very involved attentive developer!
Best app on the AppStore to estimate PPFD for growing plants. I’m a botanist, and so I know this app won’t replace a $400 par meter, but for quick estimations with your phone? This app is more than worth it. The hold feature is super useful. The background shows a grainy picture that gives you instant feedback that you are aiming your phone correctly, which is a unique feature that even the expensive PAR meters do not have. A suggestion to the developer for a future update would be for the background preview picture to freeze when the hold option is used. The hold option right now freezes the reading which is useful for measuring at actual leaf locations and orientations, but the background picture does not freeze with the reading. It would be amazing for the background image to freeze with the hold measurement, so when you pull your phone back you could see that you were aiming the phone correctly and you could see what you were aiming at when the hold measurement was taken.
4Dbox, Mar 10, 2021
Very useful in the indoor garden
It’s simple to use, has a pleasant interface, and the readings correlate to manufacturers PPFD output charts for my grow lights. Very useful for setting LED light heights. Make sure to construct the simple white paper diffuser as recommended by the developers . I wholeheartedly recommend this app.
Crankdoctor, Feb 24, 2020
Helped so much.
I tried a couple apps and nobody had one for different lighting so this was a great step above. I purchased a new grow light and had it to low and to high for a week. Almost toasted my plants. I could only find around about how high I needed it on web. I seen this app and it could read led white and red together so I was on it! Needles to say it put me in the sweet spot and plants are loving light now thanks to this app. It’s a game changer. I’m sold!

Reviews and Mentions

How to Use

Photone is used in many ways to optimize grow lighting. The following represents some examples to get you started.


Identify where and how high to hang your lamp

Learn More

Duration and Power

Regulate how long and how strong your lights are on

Learn More


Identify when a light bulb needs to get replaced or cleaned

Learn More


Photone is available for iPhone and iPad.
It's free.

Running on Android?

Photone for Android

Photone will be available for Android very soon.
Sign up to access the Beta version as soon as it is ready.