Lux to PPFD Calculator

Easily convert between illuminance (lux/fc) and PPFD (µmol/m²/s)

Illuminance measures the amount of light reaching a surface as perceived by humans. It is measured in lux (lumens/m²) or foot-candles (lumens/ft²). PPFD measures the amount of plant-usable light (PAR) your plant receives at a given moment. Since Illuminance and PPFD weight wavelengths differently, the conversion between them depends on the measured light source.

⚠️ Note: These conversion values are only rough guidelines and are based on theoretically ideal values. A lux meter doesn't even register most red and blue light because it's tuned to human vision — this leads to an erroneous conversion. For actual PAR measurements, download the Photone app to measure the accurate PPFD directly with your smartphone.

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Common lux to PPFD conversions

The table below shows PPFD values for common illuminance levels (in lux) across four common grow-light sources. For instance, 30,000 lux of sunlight equals roughly 540 µmol/m²/s PPFD, while the same 30,000 lux from a full-spectrum LED equals about 420 µmol/m²/s — the difference is driven by the source spectrum.

Illuminance (lx)	Sun/Daylight	LED Full Spectrum	High Pressure Sodium (HPS)	Fluorescent
5,000	90	70	70	65
10,000	180	140	140	130
15,000	270	210	210	195
20,000	360	280	280	260
30,000	540	420	420	390
40,000	720	560	560	520
50,000	900	700	700	650
75,000	1,350	1,050	1,050	975
100,000	1,800	1,400	1,400	1,300
Formula: PPFD = lux × light source conversion factor. PPFD rounded to integer µmol/m²/s.

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Lux to PPFD Calculator

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Common lux to PPFD conversions

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