Formula used
| Calculation | Formula |
|---|---|
| Daily Light Integral | DLI = PPFD × lighting hours × 3,600 ÷ 1,000,000 |
| Required PPFD | PPFD = target DLI × 1,000,000 ÷ lighting seconds |
| Fixture PPF | PPF = fixture wattage × photon efficacy |
| Required total PPF | PPF = electric PPFD × area × margin ÷ effective delivery |
| Energy use | kWh = total wattage ÷ 1,000 × operating hours |
| Electricity cost | Cost = energy use × electricity rate |
| Heat output | BTU/h = electrical watts × 3.412 |
How to use
- Select a plant preset and growth stage.
- Choose DLI, PPFD, or combined target settings.
- Enter the full growing area and rack count.
- Add fixture output, wattage, height, and beam angle.
- Adjust losses, dimming, electricity, and comparison details.
- Calculate, review warnings, then export the summary.
Example data
| Example | Area | Target | Photoperiod | Fixture | Purpose |
|---|---|---|---|---|---|
| Leafy greens shelf | 1.44 m² | 14 DLI | 16 hours | 300 W, 810 µmol/s | Balanced growth |
| Tomato tent | 2.25 m² | 30 DLI | 16 hours | 480 W, 1,350 µmol/s | Fruiting support |
| Houseplant corner | 0.8 m² | 8 DLI | 12 hours | 100 W, 230 µmol/s | Supplemental light |
Frequently asked questions
What is PPFD?
PPFD measures usable photons reaching each square metre every second.
What is DLI?
DLI totals daily photosynthetic light received by the plant canopy.
Should I use PPF or wattage?
PPF describes photon output. Wattage mainly describes electrical consumption.
Why does hanging height matter?
Height changes beam spread, intensity, uniformity, and possible heat stress.
Can natural sunlight reduce fixture needs?
Yes. Enter reliable natural DLI to reduce electric lighting demand.
Why can lux be misleading?
Lux follows human vision and changes differently across lamp spectra.
What does the design margin do?
It adds reserve output for losses, ageing, and imperfect distribution.
How is fixture quantity calculated?
Required delivered PPF is divided by usable fixture photon output.
Does this replace a PAR meter?
No. A calibrated PAR meter confirms actual canopy-level distribution.