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Lux = PPFD × Conversion Factor
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PPFD (Photosynthetic Photon Flux Density) to Lux conversion is a method to translate the amount of photosynthetically active radiation (measured in μmol/m²/s) into illuminance (measured in lux), which is more commonly used in lighting design and human vision applications.
The calculator uses the conversion formula:
Where:
Explanation: The conversion factor varies depending on the light source's spectral distribution, as lux is weighted by the human eye's sensitivity while PPFD measures photons in the photosynthetically active range.
Details: This conversion is important for comparing lighting requirements between plant growth applications (using PPFD) and human lighting applications (using lux), and for ensuring proper light levels in environments where both plants and people coexist.
Tips: Enter PPFD value in μmol/m²/s and the appropriate conversion factor for your light source. Both values must be positive numbers.
Q1: Why is the conversion factor not constant?
A: The conversion factor depends on the light source's spectral distribution because lux is weighted by the human photopic vision curve while PPFD counts photons in the 400-700nm range.
Q2: What are typical conversion factors for common light sources?
A: Conversion factors vary: ~54 for sunlight, ~65-75 for cool white LEDs, ~70-80 for warm white LEDs, and different values for other light sources.
Q3: When should I use this conversion?
A: Use this conversion when you need to translate between plant lighting requirements (PPFD) and human lighting measurements (lux), particularly in greenhouse or indoor growing environments.
Q4: Are there limitations to this conversion?
A: Yes, the conversion is approximate and depends on the specific spectral distribution of the light source. It's most accurate when the conversion factor is measured for the specific light source.
Q5: Can I use lux meters for plant growth measurements?
A: While lux meters are more common and affordable, they are not ideal for precise plant growth measurements as they don't accurately measure photosynthetically active radiation. Dedicated PAR meters are recommended for plant applications.