Contact Us

Keep The Guesswork Out of Grow Lighting

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

Grow Light Meter App

The Revolutionary
Grow 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

  • DLI in mol/m²d

  • 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
by htdrjigghh356 – May 14, 2021
Great app!
My problem with my soup, was actually my lighting problem. I was able to mitigate my hot and cold spots. My average DLI across my garden is now around 40. Before I had spots as low as 14 and as high as 80, yikes! After adjusting the light I was also able to turn off 60 watts of LED lightning saving energy and my plants. Highly recommended app!
by Musical Mole Dev – Apr 24, 2021
Handy App for your phone no need for extra equipment
Great little App, my grow lights are supposed to be 750 umol at 18 inches. I measured them with this app and guess what the reading was 748. I will continue to use this to place my light at the optimum height. I do wish the Kelvin feature was an IAP though. I as well as many others only need to measure LED full spectrum these days and I have now purchased the LED add on so now I have nothing left to purchase and I’m definitely not paying for yearly just to get a bonus Kelvin measurement when I don’t need the other lights. Good App though saves carrying around expensive light meters. Recommend.
by Albissett – Apr 4, 2021
Fantastic app, why o pop au £500+ for a par meter when you can spend a fiver and get amazing results.
by Mariyan P – Apr 26, 2021
Matches Manufacturer PPFD at given height
Compared to what my manufacturer claims my lights PPFD is at 12” which is around 780 and this app came to about high 700s low 800s very happy with accuracy
by 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.
by 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, iPad, and Android Smartphones.
It's free.