DLI calculator
Estimate daily light integral from PPFD and hours of light.
Use the result as a starting point.
Enter measured values, check the units, and keep the assumptions beside the answer. This tool supports a growing decision; it does not replace a calibrated meter, a product label, or observation of the crop.
Formula: PPFD × hours × 3,600 ÷ 1,000,000. Crop and room conditions determine whether a target is comfortable.
How to use this tool
Use DLI to estimate the total photosynthetic light delivered to the canopy during one 24-hour cycle.
- Enter canopy PPFD in micromoles per square meter per second and light hours from 0 to 24.
- Enter the values, check the units, and select Calculate.
- Read the result as a planning estimate, then compare it with the crop and system.
Formula or reference method
DLI = PPFD x light hours x 3,600 / 1,000,000.
Worked example
A canopy reading of 250 PPFD for 16 hours gives 250 x 16 x 3,600 / 1,000,000 = 14.40 mol/m2/day.
Understanding the result
DLI describes daily photon delivery. Compare it with the crop, cultivar, temperature, CO2, and water movement.
Assumptions and limits
A single PPFD reading may not represent the whole canopy. Light uniformity and plant age still matter.
Common mistakes
Do not substitute fixture wattage for PPFD or forget that the dark period is part of the 24-hour schedule.