Photone - Grow Light Meter: iPhone vs Android

Turn your iPhone or iPad into a PAR meter. Measure PPFD, DLI, lux, foot-candles, and color temperature (kelvin) to give your plants exactly the light they need. Trusted by millions of growers, Photone is the only accurate plant light meter app.

How much light do your plants really get? Are your lamps hung too high, dimmed too low, or on for too long? Whether you grow houseplants or use a grow tent, greenhouse, hydroponics system, or aquarium, Photone answers these questions and more.

Photone is more than just a PAR meter: it gives you the tools and guidance to understand the numbers.

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
⎷ Correlated color temperature (CCT) in kelvin *
⎷ Extended PAR (ePAR) including far-red light (ePPFD, eDLI) *

FEATURES

⎷ Industry-leading accuracy
⎷ Heatmaps — Create PAR maps, PPFD maps, DLI maps, lux maps, and export them as images or PDFs
⎷ Logging — Track measurements over time as an interactive chart, Auto-Log sessions, and export or import them
⎷ Projected DLI — Get the daily light your plants receive instantly by entering how long your lamps are on ← perfect for grow lights
⎷ Actual DLI — Leave your device in place and use Auto-Log to sum up the light throughout the day ← perfect when measuring sunlight
⎷ In-app guides
⎷ Light calculators and recommendations
⎷ Excellent low light sensitivity to detect light pollution for plants
⎷ Custom calibration option to align readings to another meter
⎷ No Bluetooth and location permission required
⎷ No ads
⎷ All grow light sources supported (Natural sunlight, LEDs, HPS, MH, etc.) *
⎷ Photone for Apple Watch — monitor live readings from your wrist *
⎷ Average and peak readings *
⎷ Hands-free "read aloud" function *
⎷ Special underwater measurement mode *
⎷ Pro support by real human experts *

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

HOW ACCURATE IS PHOTONE?

Photone matches the accuracy of professional handheld PAR quantum sensors costing hundreds of dollars. Here's how:

⎷ RAW sensor data — capture true light intensity using the camera, the most precise sensor in your device
⎷ Pre-calibrated per device model
⎷ Developed according to the ISO/CIE 19476 standard for light measurement
⎷ Continuously tested — we regularly calibrate and test on new devices

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/.

(!) Do not rely on apps that do not require a diffuser.

Turn your iPhone or iPad into a PAR meter. Measure PPFD, DLI, lux, foot-candles, and color temperature (kelvin) to give your plants exactly the light they need. Trusted by millions of growers, Photone is the only accurate plant light meter app.

How much light do your plants really get? Are your lamps hung too high, dimmed too low, or on for too long? Whether you grow houseplants or use a grow tent, greenhouse, hydroponics system, or aquarium, Photone answers these questions and more.

Photone is more than just a PAR meter: it gives you the tools and guidance to understand the numbers.

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
⎷ Correlated color temperature (CCT) in kelvin *
⎷ Extended PAR (ePAR) including far-red light (ePPFD, eDLI) *

FEATURES

⎷ Industry-leading accuracy
⎷ Heatmaps — Create PAR maps, PPFD maps, DLI maps, lux maps, and export them as images or PDFs
⎷ Logging — Track measurements over time as an interactive chart, Auto-Log sessions, and export or import them
⎷ Projected DLI — Get the daily light your plants receive instantly by entering how long your lamps are on ← perfect for grow lights
⎷ Actual DLI — Leave your device in place and use Auto-Log to sum up the light throughout the day ← perfect when measuring sunlight
⎷ In-app guides
⎷ Light calculators and recommendations
⎷ Excellent low light sensitivity to detect light pollution for plants
⎷ Custom calibration option to align readings to another meter
⎷ No Bluetooth and location permission required
⎷ No ads
⎷ All grow light sources supported (Natural sunlight, LEDs, HPS, MH, etc.) *
⎷ Photone for Apple Watch — monitor live readings from your wrist *
⎷ Average and peak readings *
⎷ Hands-free "read aloud" function *
⎷ Special underwater measurement mode *
⎷ Pro support by real human experts *

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

HOW ACCURATE IS PHOTONE?

Photone matches the accuracy of professional handheld PAR quantum sensors costing hundreds of dollars. Here's how:

⎷ RAW sensor data — capture true light intensity using the camera, the most precise sensor in your device
⎷ Pre-calibrated per device model
⎷ Developed according to the ISO/CIE 19476 standard for light measurement
⎷ Continuously tested — we regularly calibrate and test on new devices

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/.

(!) Do not rely on apps that do not require a diffuser.

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 u

This update ships minor fixes and improvements