PPFD Grow Light Calculator
Estimate PPFD and DLI for your grow light setup — in umol/m2/s and mol/m2/day.
Please enter valid dimensions and wattage.
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PPFD, the photosynthetic photon flux density, measures how much light plants can use at the canopy, in micromoles per square meter per second. It depends on how much light the fixture produces, how efficiently it converts power to usable photons, how large the area is, and how far the plants are from the light. This calculator estimates PPFD and the daily light integral from the wattage, the efficacy, and the area.
As an example, a 400 watt LED with an efficacy of 2.5 micromoles per joule produces about 1,000 micromoles per second. Spread evenly over 1.5 square meters that is roughly 670 PPFD, though real values are lower at the edges and with distance. Premium LEDs of 3.0 micromoles per joule or more deliver more light for the same power.
Typical targets are about 100 to 300 PPFD for seedlings, 300 to 600 for vegetative growth, and 600 to 1,000 for flowering crops, depending on the plant. A quantum sensor gives accurate readings at the canopy, and reflective walls help keep the light on the plants. Combine the PPFD with the hours of light to find the daily light integral.