PAR Meter: Grow Light PPFD DLI

PAR Meter is a quantum meter that measures the light your plants actually use: PPFD (Photosynthetic Photon Flux Density, µmol/m²/s) right now and DLI (Daily Light Integral, mol/m²/day) over the whole day. Choose your plant type and see at once whether the light is too weak, right or too strong, and what to do about it.

WHY MEASURE GROW LIGHT?
Plants do not grow on lux or lumens. They grow on PAR, Photosynthetically Active Radiation, the light between 400 and 700 nm that photosynthesis can use. A lamp can look bright and still deliver little usable light. Too little light gives slow, stretched, pale growth and leggy seedlings. Too much wastes electricity and can bleach or burn leaves. Measuring PPFD lets you hang your grow lamp at the right height, find the dark corners of your grow tent, check a windowsill, and compare one grow light with another. With a plant type selected, the app also recommends how many hours per day the light should be on.

KEY FEATURES
🌱 PPFD in µmol/m²/s, the photon flux at the canopy right now
📅 DLI in mol/m²/day, the total light over a day, from your light period (photoperiod)
🪴 Plant type selection with recommended DLI and PPFD ranges shown as a green, yellow and red band on the gauges
👍 Plain-language guidance: too weak, right or too strong, and whether to move the lamp, dim it or change the hours
💡 Light source types: LED grow light, daylight, household white LED, fluorescent (T5, CFL), HPS, metal halide (MH), ceramic metal halide (CMH), or your own µmol per lux factor
☀️ Illuminance in lux and foot-candles, so it also works as a lux meter
📈 Logarithmic PPFD gauge, as precise on a dim windowsill as under a strong lamp
⏸️ Hold button to freeze the reading before taking the phone out from among the plants
💾 Save measurements with timestamps and comments
🔧 Built-in calibration for optimal accuracy
📱 Uses the phone's light sensor, no camera needed (phones without a light sensor use the camera)
⚙️ Customizable settings

PLANT TYPES WITH RECOMMENDED LIGHT LEVELS
🌿 Houseplants, foliage and flowering: pothos, monstera, philodendron, ficus, peace lily, African violet
🌸 Orchids, phalaenopsis and bromeliads
🌵 Succulents, cacti, aloe and jade plants
🌱 Seedlings, cuttings, clones and propagation
🥬 Microgreens, leafy greens, lettuce, spinach and kale
🌿 Herbs: basil, mint, parsley, coriander, rosemary
🥕 Root vegetables: carrots, beets, radishes, potatoes
🍓 Fruits and berries: strawberries, blueberries, citrus
🍅 Fruiting vegetables: tomatoes, peppers, chili, cucumbers, eggplant
🌳 High light plants, vegetative and flowering stages

IDEAL FOR
🏠 Grow tents, grow rooms, windowsills and balconies
🏡 Greenhouses, hydroponics, aquaponics and vertical farming
🐠 Planted aquariums, terrariums and vivariums
🌲 Bonsai, carnivorous plants and rare houseplants
💡 Comparing LED grow lights, quantum boards and COB lamps
📐 Mapping a grow area and setting the lamp height above the canopy
🎓 Horticulture, botany and agriculture education

HOW TO USE
Place your phone flat at the top of your plants, screen facing the light, and read the PPFD. Set your light period per day to get the DLI, and select the plant type for recommendations.

ACCURACY
The app measures illuminance and converts it to PPFD with a conversion factor for each light source type, following the widely used Apogee Instruments constants. Selecting the correct light source type is the single most important setting. Optional calibration against a PAR meter or quantum sensor further enhances accuracy on your device.

FREE TO USE
Measuring PPFD, DLI and lux is free, with no time limit and no ads. Saving measurements and calibration are available with a one-time fee or subscription, still at a fraction of the cost of a dedicated PAR meter.

SUPPORT & FEEDBACK
Your feedback helps improve the app. Contact us at apps@contechity.com for support or suggestions.

Turn your phone into a grow light meter today and give your plants the light they need.