Photone - Grow Light Meter

Photone - Grow Light Meter

Perfectly light your plants!

4.9K ratings
226 reviews
Free
In-App Purchases

Details

  • Released
  • Updated
Photone - Grow Light Meter screenshot #1 for iPhone
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About

This app acts as a professional-grade light meter for plants, measuring PAR, PPFD, DLI, and more using your device's camera. It helps optimize plant lighting by providing accurate readings and in-app guides, with optional advanced features available through purchase.

Measure PAR, PPFD, DLI, lux, foot-candles, and kelvin
Research-grade accuracy using device camera
Pre-calibrated for specific devices
In-app guides and tools
Light source selection for various grow lights
Hands-free 'read aloud' function
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What users say

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+1

What's New in Photone

4.5.0

July 15, 2026

Measure your real Daily Light Integral (DLI): the Toolbox logging tool now supports day-long auto-logging and calculates the DLI from all measurements.

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Subscription plans

Photone Pro (Monthly)

Photone Pro (Monthly)

$5.491 Month
How to cancel Photone subscription ⁉️
3

In-App Purchases

$5.49

MH lifetime unlock

Metal Halide (MH) Lamp

User reviews

Can’t test sunlight for free

I made their paper diffuser and started measuring an area only to be stopped. If you want to measure sunlight, you have to pay over $5.

Nothing free about this

Whichever light you want to measure it costs , stop touting this app as free. Unless you count the free download .

You will not find better

100% perfect no quibble

Amazing app for lighting ideas

Been using this for about a week or two it’s a pretty good app works as it should however, sometimes it’s hard to hold the paper under the screen or camera and looking at the screen under the bright light. It’s hard to see the exact numbers, but I figured it out. Hopefully, it’s been fixed in the latest update props to this dev team.
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“Free” is misleading

Wanted an app to measure indoor natural light & this one rated really well. Downloaded it & discovered “sun” aka natural light is locked unless you purchase a subscription/membership. This light source is likely the most commonly used for growing plants but yet needs a subscription? No thanks.

Developer apps

User experience

🐞

Reported Bugs

3 issues

Readings don't change with proximity

Bug

Diffuser requirement not made clear upfront

Bug

Purchased features not working as expected

Bug

Requested Features

4 requests

Add calibration feature

Feature

Expand supported light types in free version

Feature

Improve accuracy across different devices

Feature

Provide a one-time purchase option instead of subscription

Feature

FAQ

What does Photone do?

Photone is a mobile application that functions as a highly accurate light meter for plants. It uses your device's camera to measure various light metrics such as PAR, PPFD, DLI, lux, foot-candles, and color temperature (kelvin). This data helps users understand and optimize the lighting conditions for their plants.

What are the key features of Photone?

Key features include industry-leading accuracy comparable to professional PAR sensors, pre-calibration for your specific device, and excellent low light sensitivity. It also offers in-app guides, light source selection for different grow lights, and a hands-free 'read aloud' function. Some advanced features like Extended PAR and underwater measurement modes require an in-app purchase.

How much does Photone cost?

Photone is free to download and use with all basic features, and it contains no ads. To unlock its full potential and access advanced features, users can opt for a one-time lifetime unlock purchase or a Pro subscription. These upgrades support the app's development and environmental initiatives.

What devices is Photone compatible with?

The app description implies compatibility with smartphones and tablets that have a camera. While specific operating system versions are not mentioned, it is generally designed to work on modern mobile devices. The accuracy of measurements can be influenced by the quality of the device's camera sensor.

What are common use cases for Photone?

Common use cases include optimizing grow light setups for indoor plants, ensuring plants receive the correct amount of light for photosynthesis, diagnosing lighting issues, and fine-tuning lighting for specific plant species. It's also useful for hobbyists and professional growers alike to achieve better plant growth and health.