Convert between lux meter readings and PPFD (μmol/m²/s) for common grow light types
| Light source | Lux per μmol/m²/s | μmol per 1,000 lux |
|---|---|---|
| Sunlight / daylight | 54 | 18.5 |
| HPS (High Pressure Sodium) | 82 | 12.2 |
| CMH / LEC | 77 | 13.0 |
| Metal Halide (MH) | 71 | 14.1 |
| White LED / Quantum Board | 72 | 13.9 |
| LED (full-spectrum / blurple) | 67 | 14.9 |
| T5 / T8 Fluorescent | 74 | 13.5 |
Formula: PPFD = Lux ÷ conversion factor | Lux = PPFD × conversion factor
Note: Lux measures visible light weighted for human vision; PAR sensors measure photons in the 400–700 nm range. For precise PPFD measurements always use a calibrated quantum sensor. Conversion factors are approximations that vary with the exact spectrum of your fixture.
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