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Free DLI calculator for optimal plant growth. Calculate daily light integral (DLI) from PPFD measurements for indoor gardens, hydroponics, grow lights, cannabis, vegetables, and seedlings. Our calculator helps you achieve the perfect light levels for maximum yields and healthy plant development.
Last updated: February 2, 2026
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Light intensity measured at plant canopy
Daily hours of light exposure (0-24)
Increase light intensity or duration for better growth.
Note: DLI measures total daily light. Same DLI can be achieved with different PPFD/photoperiod combinations.
Where PPFD is in µmol/m²/s, photoperiod is in hours, and DLI is in mol/m²/day
Flowering DLI Range
35-50 mol/m²/day
Professional cannabis growers target 40-45 DLI during flowering for maximum yields
Vegetable DLI Ranges
10-30 mol/m²/day
Leafy greens need less (10-15), fruiting vegetables need more (20-30)
Seedling DLI Range
6-12 mol/m²/day
Young seedlings need moderate light to prevent stretching without stress
Conversion Formula
PPFD × Hours × 3.6
Converts µmol/m²/s intensity to mol/m²/day total light delivery
Hydroponic DLI
15-25 mol/m²/day
Hydroponic systems can utilize higher DLI with proper nutrients
Typical LED Output
300-800 µmol/m²/s
Quality LED grow lights deliver 400-600 PPFD for most applications
For PPFD of 500 µmol/m²/s with 12-hour photoperiod:
Daily Light Integral
21.6 mol/m²/day
Equivalent Sunlight
≈ 3.0 hours
Our DLI calculator uses the standard photobiology formula to convert PPFD (Photosynthetic Photon Flux Density) measurements into Daily Light Integral values. The calculation integrates light intensity over your specified photoperiod to determine total photosynthetically active radiation delivered to plants over 24 hours.
DLI = PPFD × Photoperiod × 3.6 ÷ 1,000,000Where PPFD is in µmol/m²/s, photoperiod is in hours, 3.6 converts seconds to hours and seconds per hour, and the result is in mol/m²/day. This formula is the industry standard used by horticulturists worldwide.
Shows relationship between PPFD intensity and photoperiod duration
PPFD measures instantaneous light intensity—how many photons are hitting your plants right now. DLI accumulates this intensity over time to give you the total daily light dose. Think of it like water: PPFD is the flow rate (gallons per minute) while DLI is the total volume (gallons per day). Plants respond to both intensity and duration.
Growing other plants? Check out our raised bed soil calculator and sod calculator.
Get Custom Calculator for Your BusinessResult: DLI = 34.56 mol/m²/day
Optimal range for cannabis flowering (35-50 mol/m²/day). Consider increasing to 40-45 for maximum yields.
PPFD: 200 µmol/m²/s × 16 hours
DLI = 11.52 mol/m²/day (Perfect!)
PPFD: 600 µmol/m²/s × 14 hours
DLI = 30.24 mol/m²/day (Excellent)
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