Photone - Grow Light Meter

Photone - Grow Light Meter icon

Photone - Grow Light Meter

Lightray Innovation GmbH

4.7

9K ratings

100,000+

downloads

Free

+ in-app

In this plant light meter app, you can measure PAR, PPFD, DLI, and lux using your device’s camera. Includes in-app guides, calibration options, and light source selection.

AppRecs review analysis

AppRecs rating 4.8. Trustworthiness 78 out of 100. Review manipulation risk 26 out of 100. Based on a review sample analyzed.

★★★★

4.8

AppRecs Rating

Ratings breakdown

5 star

85%

4 star

9%

3 star

4%

2 star

0%

1 star

3%

What to know

Low review manipulation risk

26% review manipulation risk

Credible reviews

78% trustworthiness score from analyzed reviews

High user satisfaction

85% of sampled ratings are 5 stars

About Photone - Grow Light Meter

Take the guesswork out of plant lighting with Photone, the most accurate plant light meter app. Measure PAR, PPFD, DLI, lux, foot-candles, and color temperature (kelvin) directly with your phone or tablet.

To measure light with research-grade accuracy, Photone uses the most precise sensor in your device: the camera**. Its unique measurement algorithm works directly with the RAW camera sensor data to capture true light intensity. This allows Photone to rival professional handheld PAR meters in accuracy and go even further by helping you interpret the numbers with in-app guides, tools, and additional features.

MEASUREMENTS

⎷ Photosynthetically Active Radiation (PAR) as PPFD in µmol/m²/s
⎷ Daily Light Integral (DLI) in mol/m²/d
⎷ Illuminance in lux or foot-candles
⎷ Light color temperature in kelvin
⎷ Extended PAR (ePAR) including far-red light (ePPFD, eDLI) *

FEATURES

⎷ Industry-leading accuracy, comparable to professional PAR quantum sensors
⎷ Pre-calibrated for your specific device **
⎷ No ads
⎷ In-app guides
⎷ Light source selection for every type of grow light (LED, HPS, CMH, etc.) *
⎷ Average and peak readings *
⎷ Plant light calculator
⎷ Hands-free “read aloud” function *
⎷ Special underwater measurement mode *
⎷ Custom calibration option to align readings to another meter
⎷ Premium support for advanced grow questions *

* These features require an in-app purchase to fully unlock

DIFFUSER REQUIRED

Like every real light meter, Photone requires a diffuser to measure accurately**. A diffuser scatters incoming light evenly on the sensor and prevents hotspots. While it may sound complex, the solution is surprisingly easy. You have two options:

1) Easily build a diffuser yourself in less than a minute using standard printer paper. This is accurate enough for most use cases.

2) Get the dedicated Diffuser Accessory (free worldwide shipping) for best accuracy and convenience. More details on https://lightray.io/diffuser/.

** ENHANCED LIGHT MEASUREMENTS WITH THE CAMERA
Accurate light measurements with the camera require a default calibration, which is made available only for selected higher-quality devices. Check the full list of supported devices here: https://lightray.io/diffuser/compatibility/

On devices without default calibration, Photone automatically falls back to the built-in ambient light sensor (ALS). While the ALS works without an external diffuser, it is far less accurate than camera-based measurements. Learn more about the differences between the two sensor types here: https://growlightmeter.com/guides/different-light-intensity-sensors/

UPGRADE OPTIONS

Photone is free to download and use with all basic features without any ads or hidden costs. To unleash its full potential, Photone offers two types of upgrades:
→ Lifetime unlocks — one-time purchase, always restorable via your Google Account
→ Pro subscription — full access for as long as you subscribe, cancel anytime

Photone took more than 5 years of R&D to develop. Upgrading not only unlocks powerful features, but also supports future development and keeps the app ad-free for everyone. As a member of 1% for the Planet, we donate at least one percent of all revenue to environmental non-profits — so every purchase helps both your plants and the planet.

DOWNLOAD FOR FREE. TRUSTED BY MILLIONS.

Optimized for plant growers and indoor gardeners – whether you’re growing in a grow tent, greenhouse, hydroponics system, an aquarium, or are just looking for the best quantum meter app for your LED grow lights, Photone has got you covered.


Terms and Conditions: https://growlightmeter.com/terms/
Privacy Policy: https://growlightmeter.com/privacy/
Photone - Grow Light Meter Screenshots
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Reviews for Photone - Grow Light Meter

Dirt Nap

12/29/2025

App never provides accurate readings on my android phone even when calibrated.

Dan

12/27/2025

I think it works great. pretty accurate for my needs

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