## Conversion - PPFD to Lux

NOTE: The conversion from PPFD (μmol m-2 s-1) to Lux varies under different light sources. For a complete discussion please see the reference listed below.

## Conversion Factors

### Lux to PPFD (μmol m-2 s-1)

Sunlight 54 Sunlight 0.0185
Cool White Fluorescent Lamps 74 Cool White Fluorescent Lamps 0.0135
Mogul Base High Pressure Sodium Lamps 82 Mogul Base High Pressure Sodium Lamps 0.0122
Dual-Ended High Pressure Sodium (DEHPS): ePapillion 1000 W 77 Dual-Ended High Pressure Sodium (DEHPS): ePapillion 1000 W 0.0130
Metal Halide 71 Metal Halide 0.0141
Ceramic Metal Halide (CMH942): standard 4200 K color temperature 65 Ceramic Metal Halide (CMH942): standard 4200 K color temperature 0.0154
Ceramic Metal Halide (CMH930-Agro): 3100 K color temperature, spectrum shifted to red wavelengths 59 Ceramic Metal Halide (CMH930-Agro): 3100 K color temperature, spectrum shifted to red wavelengths 0.0170
Multiply the PPF by the conversion factor to get Lux. For example, full sunlight is 2000 μmol m-2 s-1 or 108,000 Lux (2000 ∗ 54). Multiply the Lux by the conversion factor to get PPF. For example, full sunlight is 108,000 Lux or 2000 μmol m-2 s-1 (108,000 ∗ 0.0185).

## PPFD to Lux Reference Table

### Lux (Fluorescent)

10 540 820 710 740
10 540 820 710 740
100 5400 8200 7100 7400
200 10,800 16,400 14,200 14,800
300 16,200 24,600 21,300 22,200
600 32,400 49,200 42,600 44,400
1000 54,000 82,000 71,000 74,000
2000 108,000 164,000 142,000 148,000

## Definitions

### Photometric Units, Illuminance

#### Foot-candle:

one lumen per square foot. The 16th General Conference on Weights an Measures (CGPM), Oct. 1979, decided that the candela is the luminous intensity of a source emitting monochromatic radiation of frequency 540 x 1012 Hz and radiant intensity 1/683 watt per steradian. This corresponds to 683 lumens per watt of radiation at approximately 555 nm wavelength, which is near the maximum of the standard photopic spectral luminous efficiency curve.

#### LUX:

one lumen per square meter; differs from foot-candle by about a factor of 10.

### Quantum Units, Photon Flux Density

#### Microeinstein:

per second and square meter (μE m-2 s-1). The einstein has been used to represent the quantity of radiant energy in Avogadro's number of photons and also Avogadro's number of photons. The second definition has the einstein equal a mole of photons. While commonly used as a unit for photosynthetically active radiation (PAR), the einstein is not an SI unit.

#### Micromole:

per second and square meter (μmol m-2 s-1). This term is based on the number of photons in a certain waveband incident per unit time (s) on a unit area (m2) divided by the Avogadro constant (6.022 x 1023 mol-1). It is used commonly to describe PAR in the 400-700 nm waveband.

### Definitions Source

Thimijan, Richard W., and Royal D. Heins. 1982. Photometric, Radiometric, and Quantum Light Units of Measure:  A Review of Procedures for Interconversion. HortScience 18:818-822.