DLI calculator: PPFD and lighting hours
Convert canopy PPFD and lighting hours into daily light integral. Add lighting periods, account for natural light and compare two schedules.
Inputs
- Supplemental DLI
- 23.04 mol/m²/d
- Total DLI
- — mol/m²/d
- Supplemental lighting duration
- 16 h
Sent only with your enquiry. The original CSV is not attached.
Periods are consecutive parts of a day, totalling at most 24 hours. Use average canopy PPFD per period. Natural DLI requires full-day measurements or a supported model; a noon PPFD reading is insufficient. Without natural DLI, the total remains unknown.
How to use it
Enter average PPFD at canopy height in µmol/m²/s. Use measurements across the growing area, not the highest reading directly under a lamp.
Enter the hours for each consecutive lighting period. Use another row when output changes; the periods together cannot exceed 24 hours.
Add measured natural DLI. Enter 0 for a fully enclosed room with no daylight; leave it blank when the daylight contribution is unknown.
A 16-hour indoor schedule
Load the worked example: 250 µmol/m²/s for 16 hours and natural DLI of 0. The calculation is 250 × 16 × 0.0036.
- Total DLI
- 14.4 mol/m²/d
- Supplemental lighting duration
- 16 h
Reading the result
The result is the daily photon total for the entered schedule. A schedule of 400 µmol/m²/s for 10 hours gives the same arithmetic total, but equal DLI does not establish equal crop performance or electricity use.
Use the toolCommon questions
Can I enter lamp wattage instead of PPFD?
No. Electrical power and canopy photon delivery are different quantities. Use a canopy PPFD measurement or a clearly identified estimate; use the energy tool for operating costs.
Why is total DLI unknown?
The natural-light field is empty. The calculator shows the artificial-light contribution separately and keeps total DLI unknown rather than assuming there is no daylight.