How lux converts to PPFD
Lux measures light as human eyes see it, so converting it to plant light (PPFD) depends on the light source. The calculator uses these approximate factors:
- Sunlight: lux ÷ 54, per Michigan State
- White or full-spectrum LED: lux × 0.0185, per Mars Hydro (approximate)
- Fluorescent tube or bulb (T5, T8, CFL): lux × 0.0135, per Mars Hydro (approximate)
- Pink or purple LEDs: lux isn’t reliable. Use the PPFD the maker publishes and the PPFD to DLI calculator.
Window light changes through the day. Take readings in the morning, at midday and in the afternoon, and use the average. How to measure light with your phone.
Lux to PPFD and DLI chart (12 hours of light)
| Lux | PPFD, sunlight | DLI, sunlight | PPFD, white LED | DLI, white LED |
|---|---|---|---|---|
| 1,000 | 19 | 0.8 | 19 | 0.8 |
| 2,500 | 46 | 2.0 | 46 | 2.0 |
| 5,000 | 93 | 4.0 | 93 | 4.0 |
| 10,000 | 185 | 8.0 | 185 | 8.0 |
| 15,000 | 278 | 12.0 | 278 | 12.0 |
| 20,000 | 370 | 16.0 | 370 | 16.0 |
| 30,000 | 556 | 24.0 | 555 | 24.0 |
Open the full DLI calculator to compare with your plant and print it