Photone - Grow Light Meter

Lightray Innovation GmbH

In-app purchases

About this app

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**. It rivals professional handheld PAR meters, and goes 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) *

TOOLBOX

⎷ Heatmaps — Create exportable PAR maps, PPFD maps, DLI maps, lux maps, and more
⎷ Logging — Track measurements over time as an interactive chart, Auto-Log sessions, and export them

FEATURES

⎷ Industry-leading accuracy
⎷ Pre-calibrated for your device model **
⎷ Excellent low light sensitivity to detect light pollution for plants
⎷ No ads
⎷ No Bluetooth and location permission required
⎷ 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
⎷ 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 here: https://growlightmeter.com/guides/different-light-intensity-sensors/

UPGRADE OPTIONS

Photone is free to download and use, with no 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 5+ years of R&D to develop. Upgrading unlocks powerful features and keeps the app ad-free for everyone. As a member of 1% for the Planet, we donate at least 1% of all revenue to environmental non-profits — so every purchase helps both your plants and the planet.

ACCURACY

Apps developed by Lightray Innovation are developed according to the ISO/CIE 19476 standard. Thanks to RAW image processing and a default calibration per device model they’re able to match the performance of high quality traditional hardware light meters. To ensure quality we rigorously test our apps regularly on upcoming devices.

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 just want 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/

Ratings and reviews

Downloaded this based on the recommendation from a YouTube video as a way to measure the output of my plant grow lights. However, full spectrum LED is locked behind a paywall, and for $75 for the one-time lifetime purchase (I'm not paying a monthly subscription for an app) I could go on Amazon and buy two physical light meters. I'm sure the app works well which is why I gave it the extra star, but I can't justify the cost.

Well heck, this does *exactly* what it claims, provides excellent & detailed information, and couldn't be easier to use- and as anybody reading this knows, an app that checks those 3 boxes is a rarity. OH, and the free version *is actually free* and has never once bombarded me with stupid ads or interrupted me to try to get me to upgrade - 🫡🤝🤘 The paid version upgrade will probably only appeal to a tiny subset of users, but rad if ye need such. Really a standout product, 11/10.

This app has been fantastic, I have the diffuser accessory now, and it made it a lot more stable. I have been using paper and it was reading quite a bit lower than it actually was and I always thought I was having to run my plants with low light and I felt bad always trying to push them thinking I was running low. Now, with the accessory, it seems to be much better. I had to raise my lights and dim one of them, and after a couple of weeks, everything is great.

What’s new

Photone now supports TalkBack and Switch Access and is more accessible than ever, so everyone can measure their light. Logging exports also get an info page in Excel, showing your measurement setup at a glance.