# 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.

PPFD (µmol m-2 s-1) to Lux

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

Lux to PPFD (µmol m-2 s-1)

Light SounceCalibration Factor
Sunlight 0.0185
Cool White Fluorescent Lamps 0.0135
Mogul Base High Pressure Sodium Lamps 0.0122
Dual-Ended High Pressure Sodium (DEHPS): ePapillion 1000 W 0.0130
Metal Halide 0.0141
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 0.0170
Multiply the Lux by the conversion factor to get PPFD. For example, full sunlight is 108,000 Lux or 2000 µmol m-2 s-1 (108,000 ∗ 0.0185).

### PPFD to Lux Reference Tables

Sunlight

If PPFD is:then, lux is:
10 540
100 5400
200 40,800
300 16,200
600 32,400
1000 54,000
2000 108,000

HPS

If PPFD is:then; lux is:
10 820
100 8200
200 16,400
300 24,600
600 49,200
1000 82,000
2000 164,000

Metal Halide

If PPFD is:then; lux is:
10 710
100 7100
200 14,200
300 21,300
600 42,600
1000 71,000
2000 142,000

Fluorescent

If PPFD is:then; lux is:
10 740
100 7400
200 14,800
300 22,200
600 44,400
1000 74,000
2000 148,000

### Phometric 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.

Definition 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.