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Conversion - PPF to Lux

 

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

Conversion Factors

PPF (μmol m-2 s-1) to Lux

Lux to PPF (μmol m-2 s-1)

Sunlight 54 Sunlight 0.0185
Cool White Fluourescent Lamps 74 Cool White Fluourescent Lamps 0.0135
High Pressure Sodium Lamps 82 High Pressure Sodium Lamps 0.0122
High Pressure Metal Halide Lamps 71 High Pressure Metal Halide Lamps 0.0141
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).

PPF to Lux Reference Table

PPF (μmol m-2 s-1)

Lux (Sunlight)

Lux (HPS)

Lux (Metal Halide)

Lux (Fluorescent)

10 540 820 710 740
10 540 820 710 740
100 5,400 8,200 7,100 7,400
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
2,000 108,000 164,000 142,000 148,000

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.