Grow Light Meter: Lux & PPFD

Find out how much light your plants really get. Lay your phone screen up where the leaves are and read PPFD, DLI, lux and foot-candles live — then see at once whether that spot suits your monstera, basil, succulents, seedlings or grow tent.

A LIGHT METER MADE FOR PLANTS
• PPFD (µmol/m²/s) — the light plants use for photosynthesis
• DLI (mol/m²/day) for the hours your light is on
• Lux and foot-candles side by side
• Large dial with zones: shade, low, medium, bright, full sun
• Hold, minimum, maximum and average
• Save readings with a button or a volume key, add notes

EVERY LIGHT SOURCE INCLUDED
Sunlight, white household LEDs, full-spectrum grow LEDs, full-spectrum + red, purple red/blue LEDs, T5/T8 fluorescent, CFL, HPS (single- and double-ended), metal halide, CMH 3100 K and 4200 K, halogen and incandescent bulbs. The same lux means different plant light under each of them, so the app converts with factors for each type (published horticulture tables).

PLANT GUIDE
• 40 houseplants, herbs, vegetables, fruit and grow-tent stages
• Target PPFD and DLI for each
• Clear advice: light is right, a bit low, far too much — move closer to the window, raise or lower the lamp

GROWER TOOLS (PRO)
• DLI logger: leave the phone under the light and see the real DLI it collects, with a chart
• Light map: measure a grow tent, shelf or window sill spot by spot — average, min, max and evenness; share as a picture
• Calibration against your own lux or PAR meter
• Your lamp's own µmol per 1000 lux from its datasheet
• Unlimited history and CSV export

HONEST ABOUT ACCURACY
Android phones measure light with the ambient light sensor next to the front camera. PPFD is an estimate from lux and the chosen light source — usually within 10–35%, which is enough to tell shade from bright light and to set your lamp height. Purple red/blue LEDs are the hardest to read. For lab-grade numbers, calibrate against a real quantum sensor. Phones without a light sensor cannot use the app.

NO ADS, NO SUBSCRIPTION
The meter, every light source and the plant guide are free, with no ads anywhere. Pro is one payment, yours forever. The app works offline and collects no personal data.