LumenLeaf: PPFD Grow Light

Free PPFD, PAR & DLI meter for monstera, microgreens, herbs & hydroponics. No ads, no account, no subscription. Honest about camera vs. ALS accuracy.

LumenLeaf turns your phone into a real PAR / PPFD grow light meter for monstera, fiddle leaf fig, pothos, snake plant, succulents, orchids, microgreens, herbs, hydroponics, grow tents and legal home cultivation — all free, offline, with no account, no ads, and no subscription.

Measure photosynthetically active radiation (PAR / PPFD), Daily Light Integral (DLI), illuminance (lux / foot-candle) and color temperature (Kelvin) directly with your phone's camera and ambient light sensor.

WHAT YOU CAN MEASURE

• PPFD in µmol/m²/s — real-time photon flux density
• DLI in mol/m²/d — daily light integral with photoperiod input
• Lux and foot-candle illuminance
• Color temperature in Kelvin (CCT)
• Per-light-source readings: Sunlight, White LED, HPS, CMH, Fluorescent, Mixed

WHY LUMENLEAF

• 100% free — every feature, every plant preset, no paywalls
• No account, no email, no sign-up
• Works fully offline
• Available in 20 languages from launch
• Honest about accuracy — we tell you when you're on camera mode vs ALS estimate
• No physical hardware to buy — interactive printer-paper diffuser walkthrough
• Zero data collection, no analytics SDK, no advertising IDs

PERFECT FOR

• Houseplant parents — monstera, fiddle leaf, pothos, snake plant, calathea, ZZ
• Microgreen growers
• Indoor herb gardens — basil, mint, rosemary, oregano
• Succulents, cacti and orchids
• Hydroponic and aeroponic setups
• Grow tent hobbyists
• Aquarium plant keepers (v1.1)
• Legal home cultivation

WHAT WE MEASURE THAT OTHER APPS HIDE LumenLeaf is the only free grow light meter that openly distinguishes camera-grade readings from ambient light sensor (ALS) estimates. If your phone does not have a calibration profile, we tell you — no silent fallback that quietly halves your accuracy.

HOW IT WORKS LumenLeaf uses your phone's rear camera in RAW mode (when supported) for research-grade illuminance, then converts to PPFD using light-source-specific coefficients. On phones without RAW support, we fall back to the ambient light sensor and clearly mark which mode you are on. A simple printer-paper diffuser is required — build one in under 2 minutes with our visual guide.