1 lux emits 1 lumen on 1 m² at a distance of 1m, but he will not emit more that 1/4 lumen at a distance of 2m and only 1/9 lumen at a distance of 3m. Lux, are used to the measurement of illuminance, that is to say the number of lumens emitted at source divided by the distance squared between the source and the illuminated surface. The candela also measures the amount of light but emitted in a certain direction, unlike the lumens that give no indication of the light distribution. A lamp 20 lm / Watt will consume 5 times more electricity than a 100 lm lamp / Watts for the same amount of light. It can also assess the performance or efficiency of the light source, when compared to Watts. This measurement is used primarily to determine the actual brightness from a source of bare light. Lumens measure the flow of light, that is to say the total amount of light generated by a device. The first units of measurement was lumens, candela and lux. The units of measure have been refined and new ones were created to measure the light intensity used by plants. We understand better now how plants use light, and the technology has evolved enough to create quality horticultural LED.

Until recently, the lack of light intensity in LEDs was a limiting factor for many gardeners and greenhouse growers indoors. Lumens, Lux, Candela, PAR, PPF, PPFD, DLI Units of measurement and terms to qualify horticultural lights.Įveryone knows what « Lumens » are from Physics class… But what about PPFD, PAR, PPF?

Lumen to candela